Three hundred and twenty-seven patients with endometrial carcinoma stage I-II were all followed for at least 5 years. The estradiol receptor concentrations were measured in 298 tumors. In 272 cases the progesterone receptor concentrations were measured as well. Both receptors were significant prognostic factors measured as 5 year survival rate. In a Cox regression test stage, degree of differentiation, myometrial invasion and age remained as independent significant factors. Progesterone receptor concentrations were almost significant in a two-sided test including all degrees of differentiation but were significant (p = 0.04) when only poorly differentiated tumors were included. Thus PgR concentrations were used only on poorly differentiated tumors. The patients could be divided into a high risk group (deep myometrial invasion), an intermediate risk group (poorly differentiated carcinomas without deep myometrial invasion but with a low progesterone receptor concentration) and a low risk group (the remaining) with 5 year survival rated of 61%, 80% and 96% respectively.