Abstract: Abstract Objective: To explore the importance of the early diagnostic value of serum β- chorionic gonadotrophin (HCG)，progesterone (P)，carcinoembryonic antigen 125 (CA125) and pregnancy-associated plasma protein (PAPP)-A in ectopic pregnancy. Methods: The serum levels of β-HCG, P, PAPP-A and CA125 were measured in 100 cases of women with atypical ectopic pregnancy, 100 cases of women with normal interuterine pregnancy (nIUP) and control group．Patients were subdivided into ＞7 weeks suppressed menstruation group and ≤7 weeks group. Data was analyzed by SPSS13.0. Results: The serum levels of CA125, PPAPP-A, P and β-HCG were significantly higher in interuterine pregnancy group than those of ectopic pregnancy group. In interuterine pregnancy group there was a lower serum level of β-HCG in ≤7 weeks suppressed menstruation group than that of ＞7 weeks group (P<0.001). There was a positive correlation between days of suppressed menstruation and the levels of β-HCG and PAPP-A. In ectopic pregnancy group there were no significant differences in the serum levels of β-HCG, PAPP-A, P and CA125 between ≤7 weeks suppressed menstruation group than that of ＞7 weeks group (P>0.05). There was no correlation between the 4 serum marker and the days of suppressed menstruation. The diagnostic critical value was CA125≤34.925U/mL, diagnostic sensitivity was CA125:80% and the specificity was CA125:73.2% in ectopic pregnancy group. The diagnostic critical value was PAPP-A≤5.405mU/L, diagnostic sensitivity was PAPP-A:76% and the specificity was PAPP-A:73.2% in ectopic pregnancy group. The diagnostic critical value was β-HCG≤4761.4mIU/mL，diagnostic sensitivity was β-HCG92% and the specificity was β-HCG:81.3% in ectopic pregnancy group. The diagnostic critical value was P≤17.21ng/mL，diagnostic sensitivity was P:96% and the specificity was P:100.0%. in ectopic pregnancy group. Conclusion: The serum levels of β-HCG，P, CA125 and PAPP - A can be used as diagnosis markers of ectopic pregnancy, in which the serum level of P or P combined with β-HCG was the best.

Key words: Beta- people human chorionic gonadotropin (β-HCG), progesterone (P), cancer embryo antigen（CA125）, pregnancy associate plasma protein-A（PAPP - A ）, ectopic pregnancy