Three types of fertility control, surgical sterilization, hormonal chemosterilization, and immunosterilization, are reviewed with regard to their potential for controlling problematic populations of carnivores. The fertility control agent and delivery protocol of choice may vary considerably according to: (i) the reason for control; (ii) the degree, urgency and duration of population reduction required; (iii) concerns about ethics and public opinion; and (iv) the status, population dynamics, social structure, mating system, size, behaviour and reproductive endocrinology of the target animals. Although they are often perceived and advocated as more preferable methods of population control than lethal approaches, it is important that wildlife managers as well as members of the public realize that the ethical acceptability of the various fertility control techniques may differ considerably - and that numerous questions regarding their effectiveness, humaneness and ecological safety remain unanswered.