Many plant substances are known for their interference with the reproductive system. Mikania glomerata is a plant popularly used to treat respiratory diseases and is reported to have flavonoids and coumarin, which have been shown to have antifertility activity in male dogs and female rats, respectively. This work analyzes the effect of a high dose of M. glomerata extract administered during the spermatogenic cycle of rats. Adult Wistar rats were treated with 1 mL of a M. glomerata extract at a dose level of 3.3 g/kg of body weight for 52 days. Body and organ weights, sperm production, circulating testosterone level and food consumption were evaluated. The results showed that the administration of the M. glomerata extract during the rat spermatogenic cycle did not significantly alter the body and organ weights nor did it interfere with gamete production, serum testosterone level or food intake.