Objective To compare PC-12 cells’apoptosis caused by the serotonin herbicides atrazine (ATR), simazine (SIM) and cyanazine (CYA). Methods The rat adrenal medullary pheochromoma PC-12 cell line was selected for routine culture. At the cell logarithmic growth phase, ATR, SIM and CYA were used at a concentration of 200 μmol/L for 24 h, respectively, and the same solvent was added in the control group. The CCK-8 method was used to detect the cell survival rate; the content of reactive oxygen species (ROS) in PC-12 cells was detected; the Real-time PCR and Western blotting methods were used to detect the mRNA and protein expressions of Bax, p53, Bcl-2 and Caspase-3. Results Compared with that in the control group, the survival rate of the cells in ATR group, SIM group and CYA group was significantly decreased. The intracellular ROS activity of the three groups was significantly increased, and the mRNA and protein expressions of Bax,p53 and Caspase-3 were increased. mRNA and protein expressions of Bcl-2 were significantly reduced (P<0. 01) . Compared with that in ATR group, the cell survival rate of SIM group and CYA group was significantly increased, the intracellular ROS activity of the two groups was significantly decreased, the expressions of Bax, p53 and Caspase-3 mRNA and protein were significantly reduced, and the expressions of Bcl-2 mRNA and protein were significantly increased (P<0. 01). Compared with that of SIM group, the cell survival rate of CYA group was significantly increased, while the intracellular ROS activity was significantly decreased; the Bax, p53 and Caspase-3 mRNA and protein expressions were significantly reduced, and Bcl-2 mRNA and protein expressions were significantly increased (P<0. 01). Conclusion ATR,SIM and CYA can all promote PC-12 cells’apoptosis; ATR has the strongest effect while CYA has the weakest effect. [ABSTRACT FROM AUTHOR]