The present study was carried out to evaluate the effective concentration of aqueous extract of Aegle marmelos leaves on male reproductive system of albino rats. The study was divided into three groups of six animals each. The first group (I) received distilled water serve as control. The second and third groups (II and III) of animals were administered the aqueous leaf extract daily at 250mg/kg body wt. and 350mg/kg body wt., respectively for a period of 45days. Significant decreases in the weights of testis, epididymes and seminal vesicle were observed. A dose related reduction in the testicular sperm count, epididymal sperm count and motility and abnormal sperm count were observed. The results showed that Aegle marmelos has effects on male rat reproduction, affecting the sexual behavior and epididymal sperm concentration.