The plasma oestrone and oestradiol levels of 34 postmenopausal women were studied and related to various of their other characteristics. The plasma oestrone and oestradiol-17beta levels (Mean +/- SE) were, respectively, 32.09 +/- 4.6 pg/ml and 13.9 +/- 3.1 pg/ml. There was a highly significant negative linear association between the years elapsed since the menopause and oestrone levels (P less than 0.001) and oestradiol levels (P less than 0.02). Both plasma oestrone and oestradiol levels were directly related to weight, but the relation was only significant for oestradiol. A significant positive correlation was found between vaginal bleeding and excess weight. The degree of oestrogenicity of the vaginal smear was directly related to the levels of oestrone (P less than 0.08) and oestradiol (P less than 0.005) and to the degree of endometrial hyperplasia (P less than 0.02).