In a retrospective study the outcome of non-gonococcal infectious arthritis was evaluated in 76 adult patients admitted to the Leiden University Hospital between 1970 and 1984. The mortality rate was 12%, and complete recovery was achieved in only 19 of the 76 patients (25%). Each of the following had a significantly unfavourable influence on the residual joint function: duration of infection more than 14 days, female sex, presence of rheumatoid arthritis, and presence of a joint prosthesis.