Objective: To explore the diagnostic value and measurement of serum CA-125, the single measurement of progesterone (P),ß-HCG, and estradiol (E2) in the early diagnosis of ectopic pregnancy. Methods: Serum levels of CA-125, progesterone, ß-HCG and estradiol were measured by Enzyme Linked Immuno Sorbent Assay (ELISA) techniques in 40 symptomatic women with ectopic pregnancy and 24 women with normal intrauterine pregnancy during gestational age of 4-10 weeks at Al-Kadhmiya Teaching Hospital, Baghdad, Iraq, between November 2010 and June 2011. Results: The mean ±SEM serum levels of CA-125, progesterone, ß-HCG, and estradiol in patients with ectopic pregnancies (16.51±2.39U/ml; 2.54±0.47ng/ml; 72.75±12.27mIU/ml; 13.4±2.14pg/ml; respectively) were significantly lower than the levels in normal intrauterine pregnancies (74.25±18.5U/ml; 28.36±3.7ng/ml; 249.54±18.0mIU/ml; 112.7±23.6pg/ml; respectively). When using a CA-125 concentration of 20.5 U/ml as a cut-off value for the diagnosis of ectopic pregnancy, sensitivity was 75.7%, specificity 100%, the positive predictive value was100% and the negative predictive value 71.4%. Conclusion: The measurement of CA-125 and progesterone levels is useful in discriminating ectopic from normal gestations.