An attempt at correlating atmospheric temperature, humidity and histologically diagnosed anovulatory endometrium has been made. A total of 140 women who had anovulatory endometrium among 1036 patients who had a clinical diagnosis of primary infertility, over a 5 yr period were studied. The principle of Edwards' test was used to analyse the seasonal trends and the seasonal index for the occurrence of anovulatory endometrium, atmospheric temperature and humidity was calculated using the average percentage method. The results suggest that anovulatory cycles in women with infertility tended to occur more during those months in the year when temperature increased (r = 0.63). However, humidity was not related to anovulation.