SUMMARY: Toxic effects of anti-cancer and other drugs on the normal tissues could be reduced by the herbal plants and their fractions. This study investigated the protective effect of Tribulus terrestris (TT) on Cisplatin- induced cytotoxicity germ cell apoptosis in male mice. In this experimental study, thirty male Balb/c mice were divided randomly into 5 groups (n=6). A single dose of Cisplatin (5.5 mg/kg) and different concentrations of Tribulus terrestris were administrated for 14 consecutive days. Reverse transcription polymerase chain reaction (RT-PCR) of apoptosis-re-lated genes was performed with RNA extracted from testes of the mice. Statistical analysis was done using one-way ANOVA. In the Cisplatin group, there was a significant increase in mRNA expression of p53 (P=0.008), bax (P=0.004) and the ratio of bax/Bcl-2 (P=0.000), whereas there was a decrease in the expression of Bcl-2 (P=0.003), as compared to control group. In Cis+TT groups, the data showed that different concentrations of TT could improve the harmful effects caused by the Cisplatin. The best protective effects were achieved in Cis+TT (300 mg/kg). Tribulus terrestris protects testicular germ cell against Cisplatin induced apoptosis by affecting related genes regulation.