Obesity is now considered to be a global epidemic. The problem of obesity has significant implications for the diagnosis and treatment of gynaecological cancer. The cancer most frequently associated with obesity is that of the endometrium. The risk of endometrial cancer is 2-3 times higher in overweight and obese women. Obesity also adversely affects survival in most studies. With regard to ovarian cancer the evidence is inconsistent. Obesity in young adulthood may be more important than that in later life. With regard to survival obesity has an adverse effect but not in early stage disease. Few data are available regarding cervical cancer and obesity. There is evidence that obesity is associated with adenocarcinoma rather than squamous carcinoma. Data on vulval cancer and obesity are scant.