The present experimental design was set up to examine the effect of Ochratoxin A on the onset of reproductive maturity and the ovarian steroidogenic capacity by means of histochemical studies. Ochratoxin A treatment causes a remarkable delay in sexual maturation as evidenced by the age at vaginal opening and appearance of first estrus (cornifid smear). The same treatment also results in a significant diminution of the delta 5-3 beta-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase activity along with a reduction in the weight of ovary, uterus, and pituitary. On the basis of above data it is assumed that the probable cause of delayed maturation in Ochratoxin A treated rat is due to the suppressed ovarian steroidogenesis.