diff --git a/tests/test_decision_curve_dcurves_parity.py b/tests/test_decision_curve_dcurves_parity.py
new file mode 100644
index 00000000..57f62263
--- /dev/null
+++ b/tests/test_decision_curve_dcurves_parity.py
@@ -0,0 +1,146 @@
+"""Regression tests for dcurves compatibility (issue #127)."""
+
+from importlib import resources
+
+import numpy as np
+import polars as pl
+from dcurves import dca
+from numpy.testing import assert_allclose
+
+from rtichoke.performance_data.performance_data_times import (
+    prepare_performance_data_times,
+)
+
+
+def _load_dcurves_survival_data() -> pl.DataFrame:
+    data_resource = resources.files("dcurves").joinpath("data/df_surv.csv")
+    with resources.as_file(data_resource) as path:
+        return pl.read_csv(path)
+
+
+def _rtichoke_survival_dca(data: pl.DataFrame, by: float) -> pl.DataFrame:
+    return (
+        prepare_performance_data_times(
+            probs={"cancerpredmarker": data["cancerpredmarker"].to_numpy()},
+            reals=data["cancer"].cast(pl.Int64).to_numpy(),
+            times=data["ttcancer"].to_numpy(),
+            fixed_time_horizons=[1.5],
+            by=by,
+        )
+        .filter(
+            (pl.col("reference_group") == "cancerpredmarker")
+            & (pl.col("stratified_by") == "probability_threshold")
+        )
+        .sort("chosen_cutoff")
+    )
+
+
+def _dcurves_survival_dca(data: pl.DataFrame, thresholds: list[float]):
+    """Call dcurves at the test boundary without requiring Polars->pandas conversion."""
+    # dcurves requires a pandas DataFrame and already depends on pandas itself.
+    # Building it from plain Python data avoids adding pyarrow just for
+    # `pl.DataFrame.to_pandas()`.
+    pandas_df_type = type(
+        dca.__globals__["pd"].DataFrame()
+    )
+    pandas_data = pandas_df_type(data.to_dict(as_series=False))
+
+    return dca(
+        data=pandas_data,
+        outcome="cancer",
+        modelnames=["cancerpredmarker"],
+        thresholds=thresholds,
+        time=1.5,
+        time_to_outcome_col="ttcancer",
+    )
+
+
+def test_survival_decision_curve_matches_dcurves_issue_127() -> None:
+    """Match dcurves TP/FP rates and net benefit on its 1.5-year example."""
+    data = _load_dcurves_survival_data()
+    thresholds = [0.00, 0.01, 0.05, 0.10, 0.20, 0.50]
+
+    dcurves_result = _dcurves_survival_dca(data, thresholds)
+    dcurves_model = (
+        dcurves_result[dcurves_result["model"] == "cancerpredmarker"]
+        .sort_values("threshold")
+        .reset_index(drop=True)
+    )
+
+    rtichoke_result = _rtichoke_survival_dca(data, by=0.01).filter(
+        pl.col("chosen_cutoff").is_in(thresholds)
+    )
+
+    assert data.height == 750
+    assert rtichoke_result.height == len(thresholds)
+
+    rtichoke_prevalence = (
+        rtichoke_result.filter(pl.col("chosen_cutoff") == 0.0)
+        .select(pl.col("real_positives") / pl.col("n"))
+        .item()
+    )
+    dcurves_prevalence = dcurves_model["prevalence"].iloc[0]
+
+    assert round(dcurves_prevalence, 2) == 0.22
+    assert_allclose(rtichoke_prevalence, dcurves_prevalence, rtol=0, atol=1e-10)
+
+    assert_allclose(
+        rtichoke_result["true_positives"].to_numpy()
+        / rtichoke_result["n"].to_numpy(),
+        dcurves_model["tp_rate"].to_numpy(),
+        rtol=0,
+        atol=1e-10,
+    )
+    assert_allclose(
+        rtichoke_result["false_positives"].to_numpy()
+        / rtichoke_result["n"].to_numpy(),
+        dcurves_model["fp_rate"].to_numpy(),
+        rtol=0,
+        atol=1e-10,
+    )
+    assert_allclose(
+        rtichoke_result["net_benefit"].to_numpy(),
+        dcurves_model["net_benefit"].to_numpy(),
+        rtol=0,
+        atol=1e-10,
+    )
+
+
+def test_survival_decision_curve_includes_prediction_equal_to_threshold() -> None:
+    """Keep dcurves' prediction >= threshold convention at an exact boundary."""
+    data = pl.DataFrame(
+        {
+            "cancer": [True, False, True, False, False, False],
+            "ttcancer": [0.5, 2.0, 0.7, 2.0, 2.0, 2.0],
+            "cancerpredmarker": [0.20, 0.20, 0.30, 0.10, 0.40, 0.05],
+        }
+    )
+
+    dcurves_result = _dcurves_survival_dca(data, [0.20])
+    dcurves_model = dcurves_result[
+        dcurves_result["model"] == "cancerpredmarker"
+    ].iloc[0]
+
+    rtichoke_result = _rtichoke_survival_dca(data, by=0.10).filter(
+        pl.col("chosen_cutoff") == 0.20
+    )
+
+    assert rtichoke_result.height == 1
+    assert_allclose(
+        rtichoke_result["true_positives"].item() / rtichoke_result["n"].item(),
+        dcurves_model["tp_rate"],
+        rtol=0,
+        atol=1e-10,
+    )
+    assert_allclose(
+        rtichoke_result["false_positives"].item() / rtichoke_result["n"].item(),
+        dcurves_model["fp_rate"],
+        rtol=0,
+        atol=1e-10,
+    )
+    assert_allclose(
+        rtichoke_result["net_benefit"].item(),
+        dcurves_model["net_benefit"],
+        rtol=0,
+        atol=1e-10,
+    )