Background and aims: Panax ginseng C.A. Meyer is a medicinal herb widely used in Asian countries. Many of its pharmacological actions are attributed to ginsenosides (saponin). However, the pharmacological effects or functions of ginsenosides on mammalian spermatogenesis are unclear. Methods:  In the present study study, we investigated the therapeutic and prophylactic effects of protopanaxatriol saponin (PT) on testicular organ weight and morphology, testicular germ cells, proliferation, differentiation and spermatogenesis after induction of toxicity by a chemotherapeutic agent, busulfan, in male mice. Results:  Intraperitoneally (IP) busulfan treatment markedly decreased the organ weight of testis, caput and cauda epididymis. After the treatment, the testes had collapsed seminiferous tubules with incomplete spermatogenesis. However, a single dose of busulfan treatment followed by PT injection showed milder damage on seminiferous tubules than busulfan alone. Conclusion:  These results suggest that PT is effective in recovery of the male reproductive organ, and induced an increase in the number and viability of germ cells overcoming busulfan toxicity. PT might have applications in the recovery of male infertility arising from azoospermia and oligospermia.