Ionising radiation exposure of 5-10gray (Gy) to the pelvic area induces premature ovarian failure (POF). Twenty-four young adult Wistar albino female rats were were treated with subcutaneous capsaicin 0.5mg/kg per day or placebo for 10days then exposed to whole body irradiation. Rats were randomly divided into four groups: (1) control; (2) capsaicin; (3) radiation only (IR): rats were injected with placebo before exposure to a single dose of 8.3-Gy whole body irradiation; (4) radiation-capsaicin (IR+CAP): rats were injected with capsaicin prior to whole body irradiation. Radiation triggered oxidative stress, increased ovarian inflammation, increased follicular apoptosis and diminished ovarian follicle pool. Capsaicin significantly ameliorated oxidative stress by decreasing serum total oxidant status, oxidative stress index, disulphide, and malondialdehyde levels (P ≤0.001); ovarian inflammatory status by decreasing expressions of TNF-α, IL-1β, PARP-1 (P =0.002); apoptosis by decreasing expressions of active caspase-3 and p53 (P =0.015, P =0.002); and follicle counts by increasing primordial follicles and decreasing apoptotic follicles (P ≤0.001) in rats when administered before radiation exposure. The beneficial effects of capsaicin are demonstrated for the first time on ionising radiation exposed rat ovaries. Capsaicin pre-treatment before radiotherapy restores the primordial follicle pool, inhibits atresia of ovarian follicles and may be an acceptable therapeutic modality to prevent radiation-induced POF.