It is well known that sexually transmitted infections of the upper genital tract are widespread. A variety of regimens are used to treat these conditions, many of which have not been subjected to randomized, prospective clinical trials (including the 1985 Centers for Disease Control [CDC] Guidelines for the treatment of upper genital tract infections [UGTI]). This investigation was undertaken to compare the 1985 CDC treatment guidelines with different doses of ceftizoxime, a third-generation cephalosporin with an intermediate half-life, plus doxycycline in patients with UGTI. The patients were divided into subgroups, depending on the presence or absence of a pelvic mass. Sixty-seven women participated in the study. They were older than 14 years of age and required hospitalization for the treatment of UGTI. These women had lower abdominal pain and tenderness, cervical motion or adnexal tenderness, and one of the following: temperature greater than 100.4 degrees F orally, leukocytosis greater than 10,500/mm3, or presence of a suspected inflammatory pelvic mass on pelvic examination or by ultrasound. Informed consent was obtained from all patients in a manner approved by the Institutional Review Board. Pelvic examinations and ultrasound evaluations of the pelvic soft tissues were performed on all patients at the time of admission. Those who were found not to have a pelvic mass or who had a pelvic mass less than 4 cm in transverse diameter were randomly allocated to receive either ceftizoxime 2 gm intravenously every 12 hours with doxycycline 100 mg intravenously twice daily (Rx 1, n = 13) or cefoxitin 2 gm intravenously every six hours with doxycycline 100 mg intravenously twice daily (Rx 2, n = 14). Those patients found to have a pelvic mass (greater than 4 cm in transverse diameter) were randomly allocated to receive either ceftizoxime 2 gm intravenously every eight hours with doxycycline 100 mg intravenously twice daily (Rx 3, n = 19) or clindamycin 900 mg intravenously every eight hours with a 2-mg/kg loading dose of gentamicin followed by 1.5 mg/kg intravenously every eight hours, with adjustments as necessary (Rx 4, n = 21). All UGTI patients without a mass treated with either Rx 1 or Rx 2 responded adequately. However, UGTI patients with a mass treated with Rx 4 were more likely than those treated with Rx 3 to require a change in antibiotics or need extirpative surgery in order to obtain a satisfactory clinical response (Fisher's exact test = 0.046, two-sided).(ABSTRACT TRUNCATED AT 400 WORDS)