Study of the chromosomal content of endometrial cells by means of three methods—direct squash, tissue culture squash, and air-dried cell suspension—showed consistent pattern of 46XX. Aneuploidy was associated with broken cells; it was not characteristic of endometrial cells associated with amenorrhea, habitual abortion, infertility of unknown origin, or abnormal hormonal state. Caution is urged in interpretation of aneuploidy, especially from squash preparations.