OBJECTIVE To demonstrate the protective effect of triptorelin, a GnRH analogue, on chemotherapy-induced ovarian gonadotoxicity. METHODS Twenty-four sexually mature, virgin, female FVB/NJNarl mice were divided into four groups: busulfan (B); low-dose triptorelin plus busulfan (T(L)+B); high-dose triptorelin plus busulfan (T(H)+B); and control. Mice in the T(L)+B and T(H)+B groups were injected with 3.8 and 38 mg/kg of triptorelin subcutaneously, respectively. Four weeks later, mice in the B, T(L)+B, and T(H)+B groups were injected with busulfan intraperitoneally at a dose of 36 mg/kg. Histologic examinations were performed 4 weeks later. RESULTS Obvious destruction of ovarian structure and significant depletion of primordial, primary, and secondary follicles were demonstrated in the B group compared with the control group, affirming the gonadotoxicity of busulfan. In the T(L)+B group, a greater number of larger primordial and primary follicles were enumerated compared with the B group; however, statistical significance was not achieved. In the T(H)+B group, the number of primordial and primary follicles was significantly greater than in the B group, and the ovarian tissue in the T(H)+B group was spared, demonstrating the effect of triptorelin pre-treatment on ovarian protection. CONCLUSIONS Our results have demonstrated a dose-dependent protective effect against gonadotoxic chemotherapy of a GnRH analogue on ovarian reserve, thus suggesting a novel application of GnRH analogues in fertility preservation.