This study evaluated the safety of bio insecticide derived from Stemona curtisii Hook. 
F. and Mammea siamensis Kosterm. on reproductive system of male rat. The rats were orally 
administered with bioinsecticide at the doses of 2, 10 and 50 mg/kg body weight for 60 
consecutive days in comparison with 2 mg/kg body weight of methomyl. It was found that rats 
treated with the bioinsecticide and methomyl showed a significant decrease in testis, seminal 
vesicle and prostate weights when compared to control rats (p < 0.05). Nevertheless, a decrease 
in epididymal sperm concentration and the histopathological alterations of the rat’s testes were 
found only in rats treated with methomyl, but not with bioinsecticide.