Cyclosporine A is one of the most widely used drugs in organ transplant and oncology patients. But its use is accompanied by many toxicities. This study aimed to investigate the possible protective effect of Costus afer (C. afer) leaf extract on cyclosporine A‐induced testicular toxicity. This study was carried out on 40 adult male Wistar rats were divided into four groups: control, C. afer, cyclosporine A and cyclosporine A+ C. afer groups. The investigations include genital weight, sperm count and characters, serum luteinising hormone (LH) and testosterone, testicular tissue contents of reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx) and lipid peroxidation (MDA). Besides, a histopathological examination of testicular tissue stained with haematoxylin and eosin (H & E) was performed. Cyclosporine A+ C. afer group showed a significant increase in the genital weight, serum testosterone, sperm count, motility and viability. Besides, the extract significantly decreased testicular content of MDA and increased SOD, CAT and GSHPx. C. afer coadministration significantly decreased serum LH and sperm abnormalities and protected against testicular histopathological alterations. The extract showed a protective effect against testicular toxicity associated with cyclosporine A and that was through an antioxidant mechanism.