Aim: To determine the ultrastructural effects of sildenafil on the female genital organs. Methods: Twenty female cycling Wistar albino rats weighing 250 +/- 20 g were randomly divided into two groups of 10 each. Rats of one group were gavaged with 0.5 mg.kg(-1).d(-1) of sildenafil 3 days in a week for 4 weeks and the other served as the controls. After cessation of treatment animals were sacrificed by cervical dislocation under methoxyflurane anaesthesia. The clitoris, vagina, uterus and bartholin glands were taken at the estrous and were fixed with 10 % formalin solution for light microscopy and 2.5 % glutaraldehyde and osmic acid for electron microscopy. Results: Under the light microscope, the fibrocollageous tissue was found increased, the capillaries enlarged and the connecting tissue elements increased in the corpus cavernosum in the treated group. On electron microscopy, increased connective tissue, fibroblasts with notched nucleus, shorten immature collagen fibers without striation were seen. Abundant foldings and penetration with collagen bundles were observed in the basal membrane. Large connection complexes, especially gap junctions among the wide capillary endothelial cells were observed. Conclusion: There are evident histological changes due to sildenafil citrate in female rat corpus cavernosum. The clitoris and bartholin glands were the most effected organs. While the histopathological changes of clitoral tissue could be expected, an increase in the mass of bartholin gland was surprised.