PIP: A method for determining fetal sex by identification of Y-chromosome bodies with quinacrine dihydrochloride stain is reported. Amniotic fluid samples were obtained from 170 antenatal cases, and the results were confirmed at birth or abortion. The accuracy of fetal sex diagnosis was 100% for samples obtained at 20-40 weeks of pregnancy and 98% for those obtained at Weeks 14-20. A drawback of the procedure is the high cost of the fluorescent microscope used to detect the fluorescent Y-chromosome bodies.