This study investigated the effect of a 3-month treatment with Withania somnifera on apoptosis and intracellular reactive oxygen species (ROS) concentration of spermatozoa and the metal ions copper, zinc, iron and gold in seminal plasma from infertile men (normozoospermic, n=25; oligozoospermic, n=25; and asthenozoospermic, n=25). The apoptotic and necrotic cell distribution were analysed by annexin-V binding and propidium iodide uptake using flow cytometry. ROS generation was measured by fluorescence intensity and metal ions were analysed by atomic absorption spectrophotometry. The results demonstrated that, prior to treatment, sperm apoptosis and intracellular ROS concentrations were significantly higher in all groups of infertile men compared with controls (P<0.01 to P<0.001). Similarly, the concentrations of the essential metal ions Cu(2+), Zn(2+), Fe(2+) and Au(2+) in seminal plasma were lower. Treatment with W. somnifera significantly reduced apoptosis in normozoospermic and oligozoospermic men and ROS concentrations in oligozoospermic and asthenozoospermic men (all P<0.05). Treatment also significantly improved metal ion concentrations in infertile men (P<0.01). It is concluded that W. somnifera improves semen quality by reducing oxidative stress and cell death, as well as improving essential metal ion concentrations. The aim of this study was to investigate the effect of 3-month treatment with Withania somnifera on apoptosis and intracellular reactive oxygen species (ROS) concentration in spermatozoa from infertile men. Before and following treatment, sperm apoptosis and concentrations of intracellular ROS and the metal ions copper, zinc, iron, and gold in seminal plasma were measured. The apoptotic and necrotic cell distribution were analysed by annexin-V binding and propidium iodide uptake using flow cytometry. ROS generation was measured by fluorescence intensity and metal ions were analysed by atomic absorption spectrophotometry. The results demonstrated that prior, to treatment, apoptosis and intracellular ROS concentrations were significantly higher in all groups of infertile men compared with controls. Similarly, the concentrations of the essential metal ions Cu(2+), Zn(2+), Fe(2+) and Au(2+) in seminal plasma were lower. Treatment with W. somnifera significantly reduced apoptosis and ROS concentrations and improved metal ion concentrations in infertile subjects. It is concluded that W. somnifera improves semen quality by reducing oxidative stress and cell death and improving essential metal ion concentrations.