The prevalence of systemic lupus erythematosus (SLE) was estimated from a secondary analysis of data collected during the Third National Study of Morbidity Statistics from General Practice, 1981-2. A total of 20 cases, all female, were seen by general practitioners during the study period. The period prevalence of SLE was 12.5/100,000 among women of all ages and 17.7/100,000 among women aged 15 to 64. These rates are lower than those reported from other developed Western countries; this is probably due to misclassification in diagnosis or prior referral of cases to consultants for chronic care, or both.