diff --git a/src/database/runs.py b/src/database/runs.py
new file mode 100644
index 00000000..6a4989cc
--- /dev/null
+++ b/src/database/runs.py
@@ -0,0 +1,36 @@
+from collections.abc import Sequence
+from typing import cast
+
+from sqlalchemy import Connection, Row, text
+
+
+def get_run(run_id: int, expdb: Connection) -> Row | None:
+    """Check if a run exists. Used to distinguish 571 (run not found) from 572 (no trace)."""
+    return expdb.execute(
+        text(
+            """
+            SELECT rid
+            FROM run
+            WHERE rid = :run_id
+            """,
+        ),
+        parameters={"run_id": run_id},
+    ).one_or_none()
+
+
+def get_trace(run_id: int, expdb: Connection) -> Sequence[Row]:
+    """Fetch all trace iterations for a run, ordered as PHP does: repeat, fold, iteration."""
+    return cast(
+        "Sequence[Row]",
+        expdb.execute(
+            text(
+                """
+                SELECT `repeat`, `fold`, `iteration`, setup_string, evaluation, selected
+                FROM trace
+                WHERE run_id = :run_id
+                ORDER BY `repeat` ASC, `fold` ASC, `iteration` ASC
+                """,
+            ),
+            parameters={"run_id": run_id},
+        ).all(),
+    )
diff --git a/src/main.py b/src/main.py
index 560b4c50..2fe219ae 100644
--- a/src/main.py
+++ b/src/main.py
@@ -11,6 +11,7 @@
 from routers.openml.evaluations import router as evaluationmeasures_router
 from routers.openml.flows import router as flows_router
 from routers.openml.qualities import router as qualities_router
+from routers.openml.runs import router as runs_router
 from routers.openml.study import router as study_router
 from routers.openml.tasks import router as task_router
 from routers.openml.tasktype import router as ttype_router
@@ -55,6 +56,7 @@ def create_api() -> FastAPI:
     app.include_router(task_router)
     app.include_router(flows_router)
     app.include_router(study_router)
+    app.include_router(runs_router)
     return app
 
 
diff --git a/src/routers/openml/runs.py b/src/routers/openml/runs.py
new file mode 100644
index 00000000..61e853a0
--- /dev/null
+++ b/src/routers/openml/runs.py
@@ -0,0 +1,56 @@
+from http import HTTPStatus
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy import Connection
+
+import database.runs
+from routers.dependencies import expdb_connection
+from schemas.runs import RunTrace, RunTraceResponse, TraceIteration
+
+router = APIRouter(prefix="/runs", tags=["runs"])
+
+
+@router.get("/trace/{run_id}")
+def get_run_trace(
+    run_id: int,
+    expdb: Annotated[Connection, Depends(expdb_connection)],
+) -> RunTraceResponse:
+    """Get the optimization trace for a run.
+
+    Returns all hyperparameter configurations tried during tuning, their
+    evaluations, and whether each was selected. Mirrors PHP API behavior.
+    """
+    # 571: run does not exist at all
+    if not database.runs.get_run(run_id, expdb):
+        raise HTTPException(
+            status_code=HTTPStatus.PRECONDITION_FAILED,
+            detail={"code": "571", "message": "Run not found."},
+        )
+
+    trace_rows = database.runs.get_trace(run_id, expdb)
+
+    # 572: run exists but has no trace data
+    if not trace_rows:
+        raise HTTPException(
+            status_code=HTTPStatus.PRECONDITION_FAILED,
+            detail={"code": "572", "message": "No trace found for run."},
+        )
+
+    return RunTraceResponse(
+        trace=RunTrace(
+            # Cast to str: PHP returns run_id and all iteration fields as strings.
+            run_id=str(run_id),
+            trace_iteration=[
+                TraceIteration(
+                    repeat=str(row.repeat),
+                    fold=str(row.fold),
+                    iteration=str(row.iteration),
+                    setup_string=row.setup_string,
+                    evaluation=row.evaluation,
+                    selected=row.selected,
+                )
+                for row in trace_rows
+            ],
+        ),
+    )
diff --git a/src/schemas/runs.py b/src/schemas/runs.py
new file mode 100644
index 00000000..30123b33
--- /dev/null
+++ b/src/schemas/runs.py
@@ -0,0 +1,22 @@
+from typing import Literal
+
+from pydantic import BaseModel
+
+
+class TraceIteration(BaseModel):
+    repeat: str
+    fold: str
+    iteration: str
+    setup_string: str
+    evaluation: str
+    selected: Literal["true", "false"]
+
+
+class RunTrace(BaseModel):
+    run_id: str
+    trace_iteration: list[TraceIteration]
+
+
+# Wraps RunTrace in {"trace": {...}} to match PHP API response structure.
+class RunTraceResponse(BaseModel):
+    trace: RunTrace
diff --git a/tests/routers/openml/runs_test.py b/tests/routers/openml/runs_test.py
new file mode 100644
index 00000000..a1e6916b
--- /dev/null
+++ b/tests/routers/openml/runs_test.py
@@ -0,0 +1,71 @@
+from http import HTTPStatus
+
+import pytest
+from starlette.testclient import TestClient
+
+
+@pytest.mark.parametrize("run_id", [34])
+def test_get_run_trace(py_api: TestClient, run_id: int) -> None:
+    response = py_api.get(f"/runs/trace/{run_id}")
+    assert response.status_code == HTTPStatus.OK
+
+    body = response.json()
+    assert "trace" in body
+
+    trace = body["trace"]
+    assert trace["run_id"] == str(run_id)
+    assert "trace_iteration" in trace
+    assert len(trace["trace_iteration"]) > 0
+
+    # Verify structure and types of each iteration — PHP returns all fields as strings
+    for iteration in trace["trace_iteration"]:
+        assert "repeat" in iteration
+        assert "fold" in iteration
+        assert "iteration" in iteration
+        assert "setup_string" in iteration
+        assert "evaluation" in iteration
+        assert "selected" in iteration
+        assert isinstance(iteration["repeat"], str)
+        assert isinstance(iteration["fold"], str)
+        assert isinstance(iteration["iteration"], str)
+        assert isinstance(iteration["setup_string"], str)
+        assert isinstance(iteration["evaluation"], str)
+        assert iteration["selected"] in ("true", "false")
+
+
+def test_get_run_trace_ordering(py_api: TestClient) -> None:
+    """Trace iterations must be ordered by repeat, fold, iteration ASC — matches PHP."""
+    response = py_api.get("/runs/trace/34")
+    assert response.status_code == HTTPStatus.OK
+
+    iterations = response.json()["trace"]["trace_iteration"]
+    keys = [(int(i["repeat"]), int(i["fold"]), int(i["iteration"])) for i in iterations]
+    assert keys == sorted(keys)
+
+
+def test_get_run_trace_run_not_found(py_api: TestClient) -> None:
+    """Run does not exist at all — expect error 571."""
+    response = py_api.get("/runs/trace/999999")
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"]["code"] == "571"
+
+
+def test_get_run_trace_negative_id(py_api: TestClient) -> None:
+    """Negative run_id can never exist — expect error 571."""
+    response = py_api.get("/runs/trace/-1")
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"]["code"] == "571"
+
+
+def test_get_run_trace_invalid_id(py_api: TestClient) -> None:
+    """Non-integer run_id — FastAPI should reject with 422 before hitting our handler."""
+    response = py_api.get("/runs/trace/abc")
+    assert response.status_code == HTTPStatus.UNPROCESSABLE_ENTITY
+
+
+def test_get_run_trace_no_trace(py_api: TestClient) -> None:
+    """Run exists but has no trace data — expect error 572.
+    Run 24 exists in the test DB but has no trace rows."""
+    response = py_api.get("/runs/trace/24")
+    assert response.status_code == HTTPStatus.PRECONDITION_FAILED
+    assert response.json()["detail"]["code"] == "572"