The aim of this study was to investigate the role of Chlamydia trachomatis as a risk factor in ectopic pregnancy in Iraqi women. The study involves two groups, the first group included 24 women diagnosed as ectopic pregnancy, while the second group included 24 women as control group diagnosed as normal pregnancy. Both groups were admitted to Al-Elweya Teaching Hospital, Baghdad from November 2009 to July 2010. Serum antichlamydial antibodies were investigated in both studied groups using enzyme_linked immunosorbent assay (ELISA). Results revealed a significant(p<0.05) percentage of IgG antichlamydial antibodies in women detected as ectopic pregnant, as compared with control normal pregnant (45 vs. 8.3%). On the other hand, ectopic pregnant women exhibited low (p<0.05)IgM antichlamydial antibodies 4% as compared with control group. In conclusion all women with seropositive to Chlamydia trachomatis antibodies had pelvic inflammatory disease (PID).