To evaluate in vivo efficacy of macrolides; erythromycin (EM) and clarithromycin (CAM), in the different treatment schedules of Chlamydia trachomatis uterine cervicitis im women. Cervical C. trachomatis was detected by the polymerase chain reaction. EM was orally administered to 8, 15 and 18 Japanese patients, at a dosage of 600 mg, t.i.d. for 5, 7 and 14 days, respectively. CAM was orally administered to 10, 26 and 19 Japanese patients at a dosage of 400 mg, b.i.d. for 5, 7 and 14 days, respectively. The eradication rate and the recurrence rate in the different treatment schedules of C. trachomatis were evaluated. The eradication rates after 5, 7 or 14 days of treatment with EM were 1/8, 8/15 or 13/18, respectively. The recurrence rates after 5, 7 or 14 days of treatment with EM were 1/1, 3/8 or 2/13, respectively. On the other hand, the eradication rates after 5, 7 or 14 days of treatment with CAM were 5/10, 26/26 or 19/19, respectively. The recurrence rates after 5, 7 or 14 days of treatment with CAM were 3/5, 0/26 or 0/19, respectively. A 7-day treatment with CAM would be adequate and effective for C. trachomatis uterine cervicitis.