The incidence of systemic lupus erythematosus, based on first hospital discharge diagnosis, in Baltimore, Maryland for the years 1970 through 1977 was determined for individual sex-race groups and the total population. Age-specific incidence rates were consistently highest among black females and lowest among white males: rates for white females exceeded those for black males through age 54, but then declined for ages ⩽55. Mean age at diagnosis was significantly lower for black females versus white females (35.5 versus 41.7 years, P = 0.005) and for all females versus all males (37.2 versus 44.2 years, P = 0.012). There were no temporal trends noted in yearly age-adjusted incidence rates during the 8-year study period. The overall population incidence of systemic lupus erythematosus was 4.6 per 100,000 per year, representing a twofold increase over a comparable study done in New York City 15 years ago.