In a nationwide study the 1982 revised ARA criteria were applied for the classification of systemic lupus erythematosus (SLE). This unselected group of patients included all cases diagnosed and managed in hospitals, as well as outside hospitals in Iceland over the 10-year period from 1975 to 1984. Seventy-six new cases were found, with an incidence of 5.9 and 0.8/100,000 for females and males at risk, respectively. The mean age at diagnosis was 46.6 years. Twenty-five percent of the patients would have been missed had the study included hospital patients only. A clinical pattern different from previous studies was found as illustrated by a low incidence of kidney disease; nephritis was found in 20% of patients. Comparison with a former study on SLE in Iceland shows an actual increase in incidence over a period of 10 years. The 5 year survival was 84% and the 10 year survival 78%.