The use of various medicinal plants in the treatment and prevention of various ailments especially in developing countries of the world cannot be overlooked. Among these medicinal plants is Mangifera indica linn. whose effect on reproductive parameters of male Wistar rats was studied in this research. Adult male wistar rats used in the study were within the weight range 150-175kg, and were divided into two groups - Group 1(G1) rats were untreated and served as control, while Group 2 (G2) were experimental rats and were orally given 10mg/kg of the aqueous extract of Mangifera indica for a period of six weeks. In the research, body weight changes were measured throughout the six weeks and it was observed at the end of the sixth week that there was a drastic reduction in the weight of the animals. It was also observed in the micrograph taken that the tunica albunigea and the basement membrane of the seminiferous tubule had been distorted, the sertoli cells and the spermatogonic cells were reduced thereby becoming scanty, there were also little and in some areas no spermatids and spermatozoa, giving a clear hyaline degeneration. It could be concluded from the above observations that mangifera indica leaf extract has adverse effects on some male reproductive parameters.