Two hundred and eight patients treated surgically for endometriosis were reviewed one to four years later. The incidence of endometriosis in this survey was 17 per cent of all gynecological laparotomies. After operation, 30 per cent of the patients were symptomless, 60 per cent estimated the alleviation as good or moderate, and only 10 per cent had no benefit from the operation. In the 32 cases where infertility was the main indication for operation and other factors affecting fertility were excluded, 20 pregnancies of 19 women were achieved after operation.