Aim: To evaluate the effects of 1,3-dinitrobenznene (mDNB) on sperm motility of hamster and to correlate the results with the fertility. Methods: Adult male hamsters were gavaged with one of the 3 dose regimes of mDNB (1.5 mg daily for 4 weeks, 1.5 mg one day a week for 4 weeks and 1.0 mg 3 days a week for 4 weeks). Computer assisted semen analysis (CASA) was used to analyse the sperm motility parameters, curvilinear velocity (VCL) and straight line velocity (VSL) of sperm in distal corpus epididymides and distal cauda epididymides. In vitro fertilisation was carded out only for 1.5 mg mDNB daily group to determine the sperm fertilising capacity. Results: There was a significant reduction in sperm velocity parameters at weeks 3 and 4 after treatment, which was correlated with a de cline in sperm fertility. Conclusion: Sperm velocity parameters may be used to determine the effect of a toxic insult on the sperm function.