We evaluated 30 patients admitted with a diagnosis of pelvic inflammatory disease (PID) by culdocentesis and ultrasonography to determine the severity of disease in relation to endocervical and culdocentesis bacteriology. Specimens from the endocervix were cultured for Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum. In addition, culdocentesis fluid was cultured for aerobes and anaerobes. Patients with N. gonorrhoeae or C. trachomatis had significantly milder disease (P less than 0.05) compared with patients whose specimens were negative for those organisms. Furthermore, those patients with ultrasound confirmation of a tubo-ovarian complex had significantly (P less than 0.0001) greater recovery of aerobes and anaerobes from culdocentesis fluid than did patients with milder disease.