The performance of various classical test theory (CTT) item discrimination estimators has been compared in the literature using both empirical and simulated data, resulting in mixed results regarding the preference of some discrimination estimators over others. This study analyzes the performance of various item discrimination estimators in CTT: point-biserial correlation, point-biserial correlation with item excluded from the test total score, biserial correlation, phi coefficient splitting total score using the median, and discrimination index. For this study, data were generated from unidimensional logistic item response theory (IRT) models with one and two parameters. The factors considered in the study were test length, intervals for item difficulty and item discrimination parameters, as well as the composition of one or two groups of the examinees with specific ability distribution parameters. Results indicate that the biserial coefficient was most highly correlated with the IRT discrimination parameter across different simulation conditions. The degree of comparability among estimators and estimator invariance varied across conditions.