The histological effect of oral administration of sildenafil citrate (Viagra), commonly used as an aphrodisiac and for the treatment of erectile dysfunction on the medial geniculate body of adult Wistar rat was carefully studied. The rats of both sexes (n=24), average weight of 202 g were randomly assigned into three treatment (n=18) and control (n=6) groups. The rats in the treatment groups ‘A’, ‘B’ and ‘C’ received respectively, 0.25, 0.70 and 1.43 mg/kg body weight of sildenafil citrate base dissolved in distilled water daily for 30 days, through orogastric feeding tube, while that of the control group D, received equal volume of distilled water daily during the period of the experiment. The rats were fed with growers’ mash obtained from Edo Feeds and Flour Mill Ltd, Ewu, Edo State, Nigeria and were given water liberally. The rats were sacrificed on day thirty-one of the experiment. The medial geniculate body was carefully dissected out and quickly fixed in 10% formal saline for histological studies. The histological findings after H&E method indicated that the treated section of the medial geniculate body showed some decreased cellular population, degenerative changes, cellular hypertrophy, with some vacuolations appearing in the stroma, with the group that received higher doses of sildenafil citrate (1.43 mg/kg) more severe. These findings indicate that sildenafil citrate consumption may have some deleterious effects on the medial geniculate body of adult Wistar rats at higher doses and by extension may affect the functions of the medial geniculate body andthis may probably have some adverse effects on auditory sensibilities by its deleterious effects on the cells of the medial geniculate body of adult Wistar rats. It is therefore recommended that further studies aimed at corroborating these observations be carried out.

Key words: Sildenafil citrate, medial geniculate body, degenerative changes, Wistar rats.