A cytologic method is described for the identification of trophoblastic epithelium in products of first-trimester abortion. In material from 50 consecutive induced first-trimester abortions, trophoblast was identified cytologically in 46 cellular samples (93.9%). In addition, nucleated fetal erythrocytes were found in 26 cellular samples (53%). There were no false positives, and three false negatives occurred. One negative examination, confirmed by histologic study, led to procedures that diagnosed ectopic tubal pregnancy. The cytologic method is easily performed and is rapid, sensitive, certain, inexpensive, and permanent. Cytologic study should not supplant meticulous macroscopic examination of abortion products by the clinician.