In a study to evaluate the possible role of Chlamydia trachomatis and Neisseria gonorrhoeae in acute salpingitis, 26% of 106 patients with severe symptoms had positive culture results for C. trachomatis; 43% of the 72 patients from whom paired sera were obtained had either positive culture results for or seroconversion in the single antigen immunofluorescence test to C. trachomatis. Twenty-six per cent of patients harboured N. gohorrhoeae and 14% had gonococcal complement-fixing antibody titres greater than or equal to 8. Intrauterine devices were used by 48% of patients, no difference being found in the frequency of use between patients harbouring C. trachomatis or N. gonorrhoeae. The possible role of C. trachomatis should be considered in the treatment of acute salpingitis.