Contraception is a critical component of population management for lemurs, but concerns about potential deleterious effects of continuous, long-term treatment with synthetic progestins such as the widely used melengestrol acetate implant led us to evaluate seasonal contraception with injections of depot medroxyprogesterone acetate (Depo-Provera, Upjohn Pharmacia, Kalamazoo, MI) to limit the duration of exposure. We compared two dosage regimens in female black lemurs using vaginal cytology as an indirect measure of ovarian suppression. Our results indicate that both 10 mg/kg body weight at 90-day intervals or 2.5 mg/kg at approximately 30-day intervals can be effective in most females, although one female on the 10-mg dose showed signs of estrus at 53 days. Darkening of pelage during treatment was the primary side effect noted. A more important observation was that contraception can extend the breeding season to as much as 9 months, considerably longer than reported previously, which necessitates extending the period of contraceptive treatment. Zoo Biol 26:289-298, 2007. (c) 2007 Wiley-Liss, Inc.