A series of taxoids (modified at the C-3'N position) have been used for the development of two QSAR models for their cytotoxic activities against macrophage (MPhi)-like cells J774.1 and J7.DEF3. QSAR results suggest that hydrophobic and steric features influence the inhibitory activity in a linear model. The ClogP values were not great enough to establish the upper limit of the inhibition. Internal [cross-validation, quality factor (Q), Fischer statistics (F), Y-randomization, and lack of overfitting tests] and external validation tests have validated both the QSAR models.