Objective To assess the clinic value of a single maternal serum beta-human chorionic gonadotropin (β-hCG) assay 11 d after embryo transfer in ART pregnancies and to predict pregnancy outcome.Methods A total of 384 pregnancies after embryo transfer were included.Inviable pregnancies were defined as biochemical pregnancies,ectopic pregnancies and first trimester abortions.Ongoing pregnancies were defined as singleton pregnancies and multiple pregnancies whose gestation were achieved more than 12 weeks.Serum β-hCG concentrations were compared among different groups.Results On the post embryo transfer d 11,the mean β-hCG concentration of the ongoing pregnancy group (323.7±285.2 mIU/ml) was significantly higher than that of the inviable pregnancy group(81.4±68.1 mmIU/ml)(P＜0.001).In multiple gestations,the levels of β-hCG were significantly higher compared with singleton pregnancies.If the β-hCG level was between 10 mIU/ml and 50 mIU/ml,the positive predictive value of biochemical pregnancies and ectopic pregnancies was 81.8%,the negative predictive value was 94.4%.If the level was less than 100 mIU/ml,the positive predictive value of first trimester abortions was 80.8% the negative predictive value was 77.8%.If the level was greater than 250 mIU/ml,the positive predictive value of multiple pregnancies was 83.3%.the negative predictive value was 74.4%.Conclusions A single serum β-hCG level on d 11 after embryo transfer has good predictive valuefor clinical pregnancy outcome in controlled ovarian stimulation cycles and helps to plan the subsequent follow-up.