Background:In modern countries today, herbal medicines are known to help in the treatment of various diseases, as rich sources of antioxidants and minerals.Objectives:To study the effect of Cinnamomum zeylanicum (C. zeylanicum) on spermatogenesis in rats.Materials and Methods:In this experimental study, Wistar male rats (n = 20) were divided into two groups, a control group (n = 10) and a Cinnamomum zeylanicum group (n = 10). The subjects in the cinnamon group received 75 mg/kg/day cinnamon by gavage for 28 days, while the controls received an equal volume of distilled water daily. Animals were kept in standardized conditions. On day 28, a 5 mL blood sample from each rat was taken from tail area to measure testosterone, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and malondialdehyde (MDA) levels. Testes were collected and were then prepared for sperm analysis by the WHO method.Results:Sperm quality parameters, total serum testosterone, SOD, CAT, and GPX levels were significantly increased in the cinnamon group in comparison to controls (P < 0.05). Also, rats in the cinnamon group showed a significant decrease in the level of plasma MDA (P < 0.05) in comparison to controls. There were no significant differences between the groups in testis weight (P > 0.05).Conclusions:The administration of 75 mg/kg/day cinnamon significantly increased the sperm population, motility and viability, which supports the theory that in mammalians, cinnamon has a beneficial effect on spermatogenesis.