Abstract Aim: To evaluate the antifertility effect ofAlstonia scholaris bark extract in male rats. Methods: In male Wistar rats Alstonia scholaris bark extract was given by oral route at a dose of 200 mg/day for 60 days. The fertility and testicular function were assessed by mating tests, sperm motility, sperm concentration, biochemical indices and testicular cell population dynamics. Results: Oral feeding with the extract at a dose of 200 mg/day for the period of 60 days did not cause body weight loss, while the weights of testes, epididymides, seminal vesicle and ventral prostate were significantly reduced. The production of step-19 spermatids was reduced by 79.6% in treated rats. The population of preleptotene and pachytene spermatocytes were decreased by 61.9% and 60.1%, respectively. Spermatogonia and Sertoli cell population were also affected. The seminiferous tubule and Leydig cell nuclear area were reduced significantly (P<0.01) when compared to the controls. Reduced sperm count and motility res Abstract: Aim: To evaluate the antifertility effect of Alstonia scholaris bark extract in male rats. Methods: In male Wistar rats Alstonia scholaris bark extract was given by oral route at a dose of 200 mg / day for 60 days. The fertility and testicular function were by mating tests, sperm motility, sperm concentration, biochemical indices and testicular cell population dynamics. Results: Oral feeding with the extract at a dose of 200 mg / day for the period of 60 days did not cause body weight loss, while the weights of The production of step-19 spermatids was reduced by 79.6% in treated rats. The population of preleptotene and pachytene spermatocytes were decreased by 61.9% and 60.1%, respectively. Spermatogonia and Sertoli The seminiferous tubule and Leydig cell nuclear area were reduced significantly (P <0.01) when compared to the controls. Reduced sperm coun t and motility res