Hyperleptinaemia of obesity is increasingly linked to numerous cardiovascular diseases and infertility. Exogenous leptin administration has been shown to adversely effect sperm count and sperm morphology in normal adult rats (Nizam et al., 2010). It is, however, unknown if these effects are reversible upon discontinuation of leptin treatment. This study therefore examined the effect of 3, 6 and 8-week recovery period on sperm count and morphology in normal adult rats following six weeks of leptin treatment. Twelve-week old male Sprague-Dawley rats were randomized into four leptin and four saline treated control groups with 6 rats in each group. Intra-peritoneal (i.p.) injections of leptin were given daily at a dose of 60 µg/kg body weight in 0.1 ml 0.9 % saline for 42 days. Controls received 0.1 ml of 0.9% saline. On day 43, one group of leptin treated rats and one group of age-matched saline treated control rats was euthanized for collection of epididymal sperm. The remaining three groups together with their age-matched saline treated controls were allowed to recover further for either 21, 42 or 56 days. Upon completion of the recovery period, animals were euthanized and the epididymis was removed and minced in 2 ml of normal saline. The suspension was then filtered through a nylon mesh and a small drop of the filtrate was placed in the center of the disc area of a Makler counting chamber and covered with a cover slip. The number of total and abnormal sperm in a strip of 10 squares was counted (x10 magnification). This represented the concentration in million per ml. Data were analyzed using ANOVA and presented as mean ± SEM. * P<0.05; **p<0.01; *** p<0.001 compared to the respective age-matched control Sperm count was significantly lower and the fraction of abnormal sperm was significantly higher in leptin treated rats on day 1 of recovery i.e. 42 days after leptin treatment. These differences were still evident at days 21 and 42 but not at day 56 of recovery. It appears the adverse effects of 42 days of leptin treatment on sperm count and morphology are completely reversed within 56 days post-treatment in Sprague-Dawley rats suggesting that the effect of leptin on sperm count and morphology includes effects further upstream in the sperm cycle, which is about 58 days in the rat.