AbstractTwo cases of meningococcal arthritis are reported, 1 an acute septic arthritis resembling gonococcal arthritis following a transient bacteremia; the other, a delayed arthritis with painless knee effusions following resolution of meningitis. Arthritis is an occasional manifestation of meningococcemia with or without meningitis. It may occur as a polyarthritis without effusion during acute septicemia, or as a subacute arthritis with effusion involving one or a few larger joints while the generalized infection subsides. The pathogenesis of these two varieties of meningococcal arthritis may be different. In rare instances, an isolated septic arthritis without typical meningococcemia is found.