Sulfur mustard (SM) is a toxic compound that can target human spermatozoa. SM induces a wide variety of pathological effects in human reproductive organs, including sexual hormone disturbance, testicular atrophy, impaired spermatogenesis, poor sperm quality, defects in embryo development, childhood physical abnormalities, and severe fertility problems. However, the molecular and cellular mechanisms of SM action on male reproductive health and human sperm function are unclear. Excessive production of reactive oxygen species and the resulting oxidative stress is likely a significant mechanism of SM action, and could be associated with sperm DNA damage, membrane lipid peroxidation, reduced membrane fluidity, mitochondrial deficiency, apoptosis, and poor sperm quality. In this review, we aim to discuss the cellular and molecular mechanisms of SM action on sperm and reproductive health, the significance of OS, and the mechanisms through which SM enhances the infertility rate among SM-exposed individuals.