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 greater than or equal to 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.