Objective To exlplore the adverse effect of formaldehyde on DNA in isolated mice testicular cells. Methods The testicular cells were exposed to formaldehyde of different concentrations(0, 25, 50, 75, 100 μmol/L), comet assay was applied to detect DNA breaks. Results Formaldehyde induced DNA bwaks at 10 μmol/L, 25 μmol/L and 50μmol/L (P〈0.05, P〈0.01, P〈0.01), DNA breaks and DNA cross-links at 75 μmol/L(P〈0.01), no significant difference in the changes of tail DNA% and tail moment had been seen between formaldehyde gronp of 100 μm...