The signs of oestrus in alpaca (Lama pacos) and llama (L. glama) are described. The results of attempts to induce ovulation by various methods (copulation by fertile and sterile males; the use of exogenous hormones; the 'male effect'; and insemination by alpaca and bovine semen) are presented. The phenomen of spontaneous ovulation is also discussed. Relations among the various mechanisms of ovulation stimuli, formation of a corpus luteum and levels and duration of peripheral progesterone are analysed. The terms 'induced or reflex' ovulation and 'spontaneous' ovulation need more careful definition. © 1994 Academic Press, Inc.