The pineal neurohormone melatonin modulates ovine reproductive seasonality, with natural increases in melatonin denoting the breeding season and subsequent escalation of fertility. Despite the commercial use of melatonin implants to promote out-of-season fertility in the ewe, their impact on the reproductive physiology of the ram remains poorly described. To remedy this, mature rams were treated with (n=14) or without (n=17) slow release melatonin implants (3 x18mg implants/ram; Regulin, CEVA Animal Health, NSW Australia) during the early non-breeding season (September). Endocrinological and reproductive parameters such as seminal plasma and blood serum melatonin levels, serum testosterone levels, testicular circumference, sperm production and quality were recorded in the weeks immediately prior to melatonin implantation, post-implantation during the non-breeding season (Sept-Dec) and again in the following breeding season (March-April). Melatonin implantation resulted in a substantial elevation of both blood serum and seminal plasma melatonin concentrations in comparison to both pre-implantation and control ram levels (P<0.001), seminal plasma melatonin remaining heightened throughout the non-breeding season (P<0.001). During this same period, melatonin-treated rams also exhibited an increase in blood serum testosterone (P<0.001). The testicular circumference of melatonin-treated rams was significantly increased throughout the non-breeding season, corresponding with an increase in total sperm production per ejaculate (P= 0.028). Control rams showed no significant change in either testes size or sperm production. No effect of treatment was observed upon sperm motility or morphology. Increased sperm production in melatonin treated rams during the non-breeding season did not negatively affect sperm production or quality in the subsequent natural breeding season. This study indicates that exogenous melatonin promotes an up-regulation of the ram reproductive axis, effectively advancing the male breeding season and improving ram sperm production in the non-breeding season.