The present study was designed to study effect of watermelon extract on fertility of experimental rats. The biological evaluation on male rats Sprague Dawley Strain (250 -270 g) the study continued for 28 days. Five groups of rats, each contains 5 rats, were fed on different tested diets Group1: control group rats fed on basal diet. Group 2: fed on basal dietand treated daily orally with 100mg/kg body weight of watermelon pulp methanol extract. Group 3: fed on basal diet and treated daily orally with 200mg/kg body weight of watermelon pulp methanol extract. Group 4: fed on basal diet and treated daily orally with 100mg/kg body weight of watermelon seeds methanol extract. Group 5:fed on basal diet and treated daily orally with 200mg/kg body weight of watermelon seeds methanol extract. Chemical, biological, biochemical and histological tests were carried out. The results of this study showed that watermelon contains high amount of moisture and carbohydrates in watermelon seeds extract and watermelon pulp extract and low amount of fat.
 
Total phenol and lycopene recorded the highest value in watermelon seeds extract. Also, phosphorus and zinc recorded the highest value in watermelon pulp extract. Testosterone, folicles timulating hormone and lutenizinghormone in all groups tested were increased significantly and significant decreased in serum prolactin hormone compared with those of the control group. The results also showed a marked significant increasesin kidney function and liver enzymes which nearly returned toward the normal (control group) levels. However, there is an increase in the feed efficiency ratio (FER) and body weight gain (BWG) in all treated groups compared to the control group although the increase was not significant. This study therefore recommend that watermelon fruit could be an excellent source of active components which may increases male fertility.