Objective(s):                 Atrazine is a widely used herbicide in agriculture. In the present study, the effects of this herbicide on the levels of pituitary-testis hormones in adult male rats were investigated. Materials and Methods:             In total, 40 male Wister rats were used. These animals were randomly divided into five groups of eight: the control group which was  left untreated, the sham group receiving solvent, and three experimental groups receiving (100mg/kg), (200mg/kg) and  (400mg/kg) dosages of Atropine,  respectively. Dosages of solvent and herbicide were injected intra peritoneally for 14 days, and afterward, blood samples were taken and serum levels of LH, FSH and testosterone were measured by RIA method. The body and testicular weights were also determined.  The mean results were evaluated by ANOVA and Tukey test among the experimental and control groups. Results:              Mean body weight showed significant decrease in experimental groups relative to control group. Testes weights were also decreased only in experimental groups receiving 200,400 (mg/kg) dosage of Atrazine. In addition, serum levels of LH showed a significant decrease in experimental groups receiving 200, 400(mg/kg) dosages of Atrazine, compared to the control group. Mean concentration FSH decresed significantly in the experimental groups receiving 400 (mg/kg) dose, while testosterone level decreased significantly in all the experimental groups, compared to the control group. Conclusion:             Atrazine can interfere with food absorption mechanisms and cause body and testicular weight loss by increasing estrogen and decreasing testosterone levels. According to the results of present study and other investigations, this herbicide probably decreases the secretion of LH, FSH and testosterone concentrations through reducing the  pituitary weight and secretion of GnRH from hypothalamus, thereby, decreasing the activities of pituitary-testis axis and spermatogenesis processes.