23 women with lower abdominal pain and Chlamydia trachomatis in the cervix, urethra, or both sites were studied. Laparoscopy was done with sampling of the endometrium and fallopian tubes for detection of C trachomatis. 11 women had laparoscopic evidence of pelvic inflammatory disease (PID); C trachomatis was detected in the upper genital tract of 8, but not in the upper tract of 5 who had laparoscopy again after treatment. The organism was also found in the upper genital tract of 9 of the 12 women without laparoscopic evidence of PID. Most of the women with abdominal pain or tenderness had tubal or endometrial C trachomatis infection, although only half had laparoscopic evidence of salpingitis. This finding suggests that antibiotic treatment should be given as soon as chlamydial infection is detected in the cervix and that pain does not necessarily point to C trachomatis in the upper genital tract. Laparoscopy may miss important pathogens in the upper genital tract, unless the procedure is complemented with detailed microbiological investigation.