AIM Cardiology nurse practitioners (NPs) conduct exercise stress tests (ESTs) for diagnosis of cardiac disease. The diagnostic concordance of NPs to cardiologists has not been assessed. The hypothesis was that an NP is as reliable as a cardiologist in determining ST-segment depression, detecting arrhythmias, and making a diagnostic assessment. METHODS An NP and two cardiologists (C1 and C2) were provided with 100 consecutive, anonymized ESTs, consisting of three 10-second, 12-lead tracings obtained at baseline, peak-exercise, and recovery. Interpretation was based on baseline rhythm, baseline and maximal exercise ST levels, arrhythmias, and global diagnosis (positive, negative, or inconclusive for ischemia). Raters used uniform criteria to interpret ESTs and were blinded to prior EST interpretation and computerized ST-segment analysis. RESULTS There was similar concordance between the NP and cardiologists as between the cardiologists, measured by Kappa coefficients (rhythm: NP vs. C1 = .92, NP vs. C2 = .84, C1 vs. C2 = .84; arrhythmias: NP vs. C1 = .77, NP vs. C2 = .73, C1 vs. C2 = .75; EST diagnosis: NP vs. C1 = .75, NP vs. C2 = .73, C1 vs. C2 = .75). Pearson correlations demonstrated concordance for baseline ST levels (NP vs. C1 = .86, NP vs. C2 = .86, C1 vs. C2 = .90) and peak exercise ST levels (NP vs. C1 = .58, NP vs. C2 = .48, C1 vs. C2 = .67). CONCLUSIONS Concordance among raters, and with the computer-generated algorithm, was moderate to high for all parameters of EST interpretation. This study lends support to NPs interpreting ESTs.