The selective use of contraception for endangered species breeding programs is a relatively new approach to wildlife management, but has many potential applications. The Save the Tasmanian Devil Program (STDP) uses contraception in their insurance metapopulation with the aims of equalising founder representation, controlling breeding within group housing situations, and preserving wild behaviours. Before this approach was taken, we conducted preliminary studies to ascertain the efficacy, duration of effect, optimal dosage, and any potential side effects of the proposed contraceptive on individual animals. This study assessed the dose-response effects of the Suprelorin® contraceptive implants containing a gonadotrophin-releasing hormone (GnRH) agonist, deslorelin, on female Tasmanian devils. Either one (n=5), two (n=5), or no (n=5) 4.7 mg implants were administered to the devils, with quarterly GnRH challenges used to test the hormonal responsiveness over two breeding seasons. There was an interactive effect of treatment group and month on the level of hormonal responsiveness (P<0.001), with treated females being suppressed relative to controls (with the exception of the mid-breeding season). At the end of the second breeding season, high dose animals were more suppressed than low dose animals, suggesting a dose-response effect. There was also an interaction between treatment and month on proportion change in body weight following contraception (P=0.013), yet there were no differences between treatment groups at each month. Contraception also had no apparent negative effects on general health measured by complete blood count analysis.