The body temperatures of 3 breeding and 7 non-breeding female hedgehogs were monitored during 3 years. Lactating females had significantly higher and less variable body temperatures than did pregnant and non-breeding hedgehogs. Breeding females had circadian body temperature cycles that were more biphasic than those of non-breeders. Females maintaining higher mean daily body temperatures showed less variability about the mean than those exhibiting lower mean daily body temperatures. The rate at which body temperatures became more variable as mean daily body temperatures fell was 4.6 times more rapid in non-breeding females than in pregnant and lactating hedgehogs. With the exception of a single female in late gestation, hedgehogs readily became torpid under conditions of low ambient temperature and short photoperiod during summer, particularly when their food intake was restricted.