Abstract: OBJECTIVE To study the cytotoxicity of dl-mandelic acid to VK2/E6E7 cells and human sperm. METHODS The high vigor sperm was incubated with dl-mandelic acid for 20 s, the sperm survival rate was evaluated by computer assistant spermanalysis(CASA). The damage of sperm surface structure was detected by scanning electron microscope. The VK2/E6E7 cells were incubated with 4.0 g?L^-1 nonoxynol-9(N-9) or dl-mandelic acid of 1.25 and 2.5 g?L^-1, the cells survival rate was evaluated by MTT assay, the release rate of LDH was detected by ELISA, and the apoptosis rate were detected by flow cytometry. RESULTS The median effective concentration and the minimal effective concentration of dl-mandelic acid to sperm were 1.25 g?L^-1 and 2.5 g?L^-1. There were no obvious damage characteristics on sperm plasmalemma or flagellum of dl-mandelic acid groups detected by scanning electron microscope, but the sperm plasmalemma or flagellum of N-9 group were severely damaged. The VK2/E6E7 cells survival rate of 1.25 g?L^-1 dl-mandelic acid group was>95%, survival rate of 2.5 g?L^-1 dl-mandelic acid group was about 50%. The LDH release rates of dl-mandelic acid groups were infinitesimal, and far below N-9 group. The living cells and late apoptotic cells of dl-mandelic acid groups were close to control group, showed no significant difference; the early apoptotic cells were little less and dead cells were little more than control group, while most cells of N-9 group were dead. CONCLUSION The dl-mandelic acid has a lower cytotoxicity to VK2/E6E7 cells than N-9. The inhibitory effect of dl-mandelic acid on sperm is not by destroying sperm plasmalemma or flagellum.