We investigated the length of time between the onset of pain symptoms and the surgical diagnosis of endometriosis in women from the UK and the USA. A total of 218 women with surgically confirmed disease, recruited through endometriosis self-help groups, completed a postal questionnaire. The mean +/- SD delay in diagnosis for women from the USA was 11.73 +/- 9.05 years, significantly higher than the equivalent delay of 7.96 +/- 7.92 years for women from the UK (P