The effects of aqueous extract of Spondias mombin leaves on testicular characteristics and neonatal birth weights after oral treatment of male and female wistar rats with graded dosages were studied. Twenty-five female and male sexually matured wistar rats divided into four treatment groups B,C, D and E and control group(A) were used. Five untreated matured male were also used for mating. The treatment groups were given 200mg/kg, 400mg/kg, 600mg/kg and 800mg/kg respectively while distill water was served to the control group for 28 days. After, testicles were harvested and studied grossly and for histology while the females were served by sexually matured untreated male rats introduced at the last half of the oral treatment. The gross and histology studies showed normal conformation of all the testicles. There was no abnormality noticed in all. Weekly vaginal cytology done during treatment revealed that all the female rats cycled normally. Births were recorded in all groups within the average gestation range of 24-28 days. While group A (control group) had the highest average litter size of 13 followed by groups D and E with 9, group C and E had the highest average birth weights of approximately 5g. It is concluded that there was no antifertility consequence of aqueous spondias mombin on the male wistar rat but insipient infertility was noticed with lower dosages for the female but none with dosage as high as 800mg/kg.