An estrous cycle length of 33 days (N = 4, range 32-34) was obtained for the common wombat from a number of parameters including vaginal smears, vaginal biopsies, changes in pouch morphology and behavioral observation. All but 1 of the successive periods of estrus occurred during winter. Hourly measurements of body temperature by telemetry showed a rhythm typical of nocturanl species. Superimposed on this diurnal rhythm was another rhythm which could be correlated with the estrous cycle.