The present study investigated the long-term effects of prenatal betamethasone exposure on sperm quality and count, fertility and plasma testosterone levels in adult male rats. Pregnant rats received 0.1 mg kg^–1 betamethasone on Days 12, 13, 18 and 19 of pregnancy. This treatment impaired sperm quality, sperm production, fertility and plasma testosterone levels in adult male offspring compared to the control group. Thus, the results of the present study indicate that the long-term effects of prenatal betamethasone exposure may be deleterious to offspring. The consequent decrease in testosterone production during adulthood, in association with damaged semen parameters, may explain for the observed decrease in the capacity of adult male offspring to themselves generate viable descendants.