Background: Malathion (MAL) is a choice insecticide in the stored grain in different countries. The aim of the present study is to evaluate toxicological effects of 30-day intake of MAL on the male reproductive system of Wistar rats.

Methods: This research was ethically approved by the local authority at Faculty of Medicine, Monastir, Tunisia. Three MAL treated groups received 1 ml corn oil containing 1.3, 13.7, and 137 mg/kg body weight/day, respectively. Body and testes weights, testosterone, Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) levels were measured. Histopathological sections were prepared from testes of animals and stained with hematoxylin and eosin and also Masson trichrome. Statistical analysis was done using SPSS for windows version 10.

Results: A meaningful decrease (p<0.05) in the testes weight of treatment groups was observed compared to the control animals. However, no significant difference (p>0.05) was found between body weight of control and treatment groups. All the three MAL-treated rats had significantly (p<0.05) lower plasma FSH, LH, and testosterone levels than the control group. Some major histopathological changes were found in testes sections of treatment groups.

Conclusion: Our study revealed that subchronic and relatively short time exposure of male Wistar rats to MAL can induce histopathological changes in testes and disturbance in sex hormones levels in a dose-dependent manner.