Subjects: To evaluate second-trimester maternal serum inhibin A levels in Asian pregnancies with fetal Down syndrome and other chromosomal abnormalities. Methods: Inhibin A level was measured from the serum samples of 25 chromosomally abnormal pregnancies, including 15 cases of Down syndrome, 4 cases of trisomy 18, 1 case of trisomy 13, and 5 cases of sex chromosome aneuploidies (4 cases of 47,XXY and 1 case of 45,X) and in a cohort of 150 controls during the second trimester of pregnancy. Results: The multiple of median levels of Down syndrome (1.74) and other chromosomally abnormal pregnancies (2.03) are significantly higher than that of normal pregnancies (p = 0.002 and p = 0.024, respectively). Only 3 of 15 (20%) Down syndrome cases had inhibin A levels at or above the 95th centile of the control values. Conclusions: Inhibin A levels are raised in Asian women affected with fetal Down syndrome and sex chromosome abnormality. In spite of the poor discrepancy of inhibin A, it might be a potential marker for Down syndrome screening in Asians.