Serum antibodies to Chlamydia trachomatis were studied by microimmunofluorescence (micro-IF) testing and by immunoblotting among 52 women with C. trachomatis cervical infection. All women underwent therapeutic abortion, and 10 (19.2%) subsequently developed laparoscopically confirmed salpingitis. Women who developed salpingitis had lower geometric mean titers of micro-IF antibody before abortion (14.9 x/divided by 2.3) than did women who did not develop salpingitis (41.6 x/divided by 4.9, P less than .01). Women who developed salpingitis significantly less often had serum IgA antibodies to a 60-kilodalton (kDa) chlamydial antigen (P = .02) and IgG antibodies to antigens of 75-kDa (P = .008), 60-kDa (P = .03), and 57-kDa (P = .0003). Serum antibodies to 100-kDa, 32-kDa, and 29-kDa antigens occurred only in women who did not develop salpingitis. Differences in antibody prevalence to specific chlamydial antigens were not due to differences in serum antibody titers between the two groups. No correlation between neutralizing sera and the risk of postabortal salpingitis was detected.