Icacinia manni or false yam grows in both tropical and temperate regions. Use of its tuber as a replacement for energy content in animal and bird feeds is being advocated. Studies show it impairs reproductive function in male rats. Possible ameliorating effect of vitamins C and E is considered in this study since oxidative stress is common metabolic pathway for many tissue dysfunctions. Twenty five male wistar rats were randomly placed into five groups of five/rats each viz control, low dose Icacinia manni, high dose Icacinia manni, high dose Icacinia manni + vitamin C and high dose Icacinia manni +vitamin E groups. Rats had free access to rat feeds and water. Animals were anaesthesized, blood samples collected and testes harvested for evaluation of relevant parameters after 28 days of treatment. P-values < 0.05 were considered statistically significant. Results showed decreased testosterone in low dose, high dose and high dose + vitamin C groups compared with control (p<0.05 each) but increased in high dose + vitamin E compared with high dose groups (p<0.05). Total sperm counts were reduced in all extract treated groups (p<0.05 each) compared with control. Sperm motility was decreased in all extract administered groups (p<0.05 each) compared with control but higher in high dose + vitamin C (p<0.05) compared with low dose group and in the high dose + vitamin C and high dose + vitamin E groups compared with the high dose extracts group (p<0.05 each). Wobbling rate increased in all extract-administered groups (p<0.05 each) compared with control and decreased in the high dose + vitamin C (p<0.05) compared with high dose group. Beat cilia frequencies decreased in all extract-administered (p<0.05) compared with control. Sperm linearity was decreased in all extract-treated groups (p<0.05 each) compared with control and reduced in the high dose, high dose + vitamin C and high dose + Vitamin E (p<0.05) compared with low dose groups but increased in the high dose + vitamin C and high dose + vitamin E (p<0.05) compared with high dose groups. Velocity of active path reduced in both low and high dose extract groups (p<0.05 each) compared with control but increased in high dose + vitamin C and high dose + vitamin E (p>0.05 each) compared with the low and high dose groups. Normomorphology was reduced in the low and high dose groups (p<0.05 each) compared with control but increased in high dose + vitamin C and high dose + vitamin E (p<0.05 each) compared with low and high dose extracts groups. In conclusion, ethanolic extract of Icacinia manni impairs male reproductive function in a dose-related matter with co-administration of vitamin C or E ameliorating some of the parameters almost at the same rate.