Accidents involving snakebites constitute a serious public health problem in many regions around the world. However, there are no study about a possible action of snake venom on the reproductive system. Herein we show that Crotalus durissus sp. (Linnaeus) rattlesnake venom (25 mu g/kg of body weight) affected chromatin condensation, and increased the number of sperm with abnormal morphology and the sperm count. In conclusion, besides the known hazards of the C. durissus sp. venom to animal health, this study was the first to show its effect also on male germ cells.