Abstract: AIM: To explore the effect of tongxinluo (TXL) on apoptosis, expression and activity of caspase-3 in palmitic acid (PA)-induced peripheral blood-derived human endothelial progenitor cells in vitro. METHODS: Total mononuclear cells were isolated from peripheral blood in vitro by Ficoll density gradient centrifugation and plated on fibronectin-coated culture dishes. After 7 days, the attached cells were divided into seven groups: one control group (normal cells), three PA groups ［attached cells were incubated with different concentrations of PA (200, 400 and 800 mol/L) for 48 h］ and three TXL groups ［attached cells were incubated with different concentrations of TXL (100, 200 and 400mol/L), respectively, for 2 h before incubation with 400 μmol/L PA for 48 h］. Flow cytometry was used to detect apoptosis. Expression and activity of caspase-3 protein were detected by Western blot and spectrophotometry, respectively. RESULTS: After exposure to PA, the apoptosis rate in treatment groups was dose-dependently higher than in the control group (P<0.05). TXL was added at different concentrations before PA incubation and cells in the TXL groups (200, 400 mol/L) showed lower apoptosis rate than in PA groups (P<0.05). Expression of caspse-3 protein and activity of EPCs in TXL groups was lower than in PA groups (P<0.05). CONCLUSION: PA promotes cell apoptosis by up-regulating expression and activity of caspase-3. TXL partly inhibits the effects of PA.