To study the cytotoxic study of anastrozole and paclitaxel-loaded nanocrystals on MDA-MB-231 cell lines for enhanced anticancer activity. Paclitaxel is a tubulin-targeting cytoskeletal drug that interferes with microtubule structures, and anastrozole’s mechanism of action is apoptosis in living cells. Methylthiazol tetrazolium (MTT) assay was used to determine anticancer activity. After 24 hours of treatment, the highest ALN and PLN concentrations (100 μg/mL) showed a cytotoxic effect. The inhibition rate of doxorubicin (standard) was found at 24 hours with 89.6. The viability values of Anastrozole loaded nanocrystals (ALN) were 14.03 (100), 22.76 (80), 28.23 (40), 34.9 (20), 40.26 (10), 50.13 (5), 60.53 (2), 80.66 (1), and 99.11 (0) μg/mL. When compared to the standard, viability was 38.23% and drug unloaded nanocrystal was 86.06% (100 μg/mL) 24 hours after anastrozole (100 μg/mL) administration to MDA-MB-231 cells. All experimental groups showed significantly from the control group. The cytotoxicity effect was determined with low dose of anastrozole and paclitaxel-loaded nanocrystals. The cell viability and toxic effects of the ALN and PLN also tested. As ALN and PLN concentrations grew, so did the harmful effect on MDA-MB-231 cell viability. Cell count was significantly reduced (p < 0.05) at high ALN and PLN concentrations (100 μg/mL). Finally, the MTT assay revealed that ALN and PLN cytotoxic to MDA- MB-231. Exposure to dose-dependently hazardous doses of ALN and PLN nanocrystal formulations resulted in increased nuclear intensity, cytochrome c, and permeability of the cell membrane in the MDA-MB-231 cell line.