"Mahkota Dewa" fruit (Phaleria macrocarpa [Scheff.] Boerl.), is a traditional Indonesian plant-based remedy that has been used traditionally for generations in treating multiple illness and diseases. This investigation intends to assess the fecundity effects of P. macrocarpa supplementation in adult male rats through hormonal, physical and histological changes. Sixty male Sprague Dawley rats were randomly distributed into two by five experimental design with two supplementation periods (3 and 7 weeks) allotted to 5 different doses of extract (0, 24, 48, 240 mg PM aqueous extract/ kg bw and 80 mg of commercial PM product/ kg bw). The mean sperm count (455 cells/ml), body weight (301 g), histological assessment of spermatogonia cells (87 cells), and thickness of seminiferous tubule layer (79 µm) significantly increased (P < 0.05) in rats treated with 240 mg/ kg dose. However, there were no changes in both physical appearances of testes (size and volume) and testosterone hormone levels among the treatment groups. Our findings indicated that supplementation of P. macrocarpa significantly increased the fecundity of rats and the effect was dose and time-dependent. The study suggested that P. macrocarpa offered an attractive and alternative potential for improving the fertility in men.