DNA flow cytometric content analysis (DFCA) and estrogen (ER) and progesterone (PR) receptor levels are reported to be prognostic with regard to the malignant potential of endometrial adenocarcinoma. We retrospectively reviewed the records of 50 patients presenting with endometrial adenocarcinoma between July 1990 and December 1992, to determine the extent of any pathologic features reported at the time of hysterectomy. Patients whose tumors were nondiploid (aneuploid) by flow cytometry generally presented with a higher pathologic stage, higher grade, and more frequent lymph node involvement. In addition, the majority of clear cell and uterine papillary serous (UPS) adenocarcinoma were also nondiploid. Fourteen of 21 ER-positive tumors aneuploid, as were 18 of 37 PR-positive tumors. We also found DNA-A (DNA content aneuploid) patterns frequently associated with tumor characteristics implicated by other authors as related to aggressiveness. Further studies comparing the molecular biology of tumors to their clinicopathologic features and behavior are needed to fully understand the ultimate malignant potential.