Onabotulinumtoxin A (onabotA) is gaining wide medical use in children. However, little is known about its potential testicular effects. The present study was planned to investigate the influence of its injection on the maturing testicular structures in rats. Immature rats were injected in the peritesticular area by onabotA with three doses of (10, 20 and 40 U/kg) three times in a two-week interval. The effect of these injections on fertility indices (sperm parameters, semen quality and testosterone levels) was examined. In addition, levels of antisperm antibodies and several apoptosis parameters were investigated. DNA content in form of ploidy was compared to control group via flow cytometric analysis