The endogenous oestrogen state in 52 women (33 with endometrial carcinoma and 19 with benign conditions of the endometrium) was assessed ny means of histological examinations of vaginal swabs and of radio-immunological determinations of 17 beta-oestradiol. Considering their age, these women displayed an oestrogen activity far exceeding that found in previous studies. There was no difference between the oestrogen levels in women with carcinoma and the other patients. Furthermore, it was stiking that in the same group of women the examined parameters frequently showed different results. Consequently, a diagnosis based solely on the investigation of one parameter must frequently be misleading.