ObjectiveTo explore the effects of several immunosuppressants on the proliferation of pheochromocytoma 12 (PC12) and L929 cells. 〖WTHZ〗Methods Different concentrations of methylprednisolone(10-3,10-4, 10-6and 10-8 mol/L), cyclosporin A(CsA,10-5 ,10-6 , 10 -7and 10-8 mol/L) and FK506 (10-6 ,10-7 , 10-8and 10-9mol/L)were administrated to the PC12 and L929 cells, while control group was given no drugs. At 24, 48 and 72 hours after administration, the cell proliferationwasmeasured with MTT methods respectively. The results were compared and analyzed statistically. Results High concentration methylprednisolone (10-3 mol/L) and low concentration CsA (10-8-10-7mol/L) could promote the proliferation of PC12 cells within 48 hours after administration, after that, the proliferation effects were no longer significant. There were no promotion effects for different concentrations of FK506. Under high concentrations, both CsA (10-6 -1×10-5 mol/L) and methylprednisolone (10-3 mol/L) could significantly inhibit the proliferationof L929 cells after 24 hours of administration. And high concentration (10-6mol/L) FK506 could promote the proliferation of L929 cells transitorily (only for 48 hours after administration). Conclusion 10-3 mol/L methylprednisolone and 10-8 -10-7mol/L CsA can promote the proliferation of PC12 cells for a short period of time. Both 10-3 mol/L methylprednisolone and 10-6-10-5mol/L CsA can significantly inhibit proliferation of L929.