Sexually active young adults with an acute arthralgia or arthritis, with or without associated skin lesions, often have disseminated gonococcal infection (DGI). In recent years, an increasing proportion of patients seen with such complaints at the University of Washington Hospitals, Seattle, have had systemic meningococcal infection rather than DGI. Among 151 patients with acute arthritis studied prospectively from 1970 to 1972, blood or synovial fluid cultures yielded Neisseria gonorrhoeae in 30 patients and Neisseria meningitidis in two. Among 62 patients meeting the same criteria who were studied prospectively from 1980 to 1983, blood or synovial fluid cultures yielded gonococci in nine and meningococci in five. Separate analysis of blood culture results from two University of Washington Hospitals also revealed a decline in the number of cases of gonococcemia from 1970 through 1984 and a shift in the relative numbers of patients with bacteremia due to N gonorrhoeae and N meningitidis. The observed decline in gonococcemia coincides with a decline in the proportion of gonorrhea in Seattle caused by gonococcal strains that have been associated with DGI. © 1987, American Medical Association. All rights reserved.