The social class distribution in 147 patients confirmed to have endometriosis at laparoscopy was done to see if the disease was associated with affluence. Two hundred and eighty-one patients confirmed not to have endometriosis was used as controls. The patients were derived from a background population for which the social class characteristics was known. Endometriosis was significantly (p < 0.001) associated with social class 1 and 2. However there was no association between social class distribution and the severity of the disease developed.