The Arabian leopard is a critically endangered species. Since there are only an estimated 200 animals remaining in the wild, careful management of the captive population is necessary to minimise inbreeding. The objective of this study was to characterise sperm morphology and ejaculate quality in captive males. Semen was collected by electroejaculation from 8 adult captive male leopards (aged 2–16 years) during the summer and winter months, and semen parameters, including sperm morphology, were assessed. Two-year-old leopards showed lower total sperm counts per ejaculate than older animals and these counts declined at >8 years. Ejaculates collected during the hot summer showed significantly lower sperm concentrations, total sperm counts, sperm motility and viability and percentage of spermatozoa showing normal morphology than ejaculates collected in the cooler winter. The results showed that the male leopard attains sexual maturity between 2 and 3 years of age and exhibits good semen quality until 8 years. Collection of semen for artificial breeding or banking would best be carried out in the cooler winter months.