In a series of 38 nonmetastasizing and 29 metastasizing endometrial cancers, histologic subtype, aneuploidy, nuclear grade, and depth of myometrial invasion were the features most distinctly separating these two groups of patients. The most important factor was histologic type: papillary, papillary serous, adenosquamous, clear cell, and diffusely infiltrating carcinomas were strongly correlated with metastasis using chi square analysis. Nuclear grade 3 and deep myometrial invasion were similar to each other in sensitivity and predictive value, and both were also strongly correlated with metastatic risk. Aneuploidy, also correlated with metastasis, was similar to nuclear grade 3 and deep myometrial invasion in predictive value but was more sensitive. DNA analysis appeared to be most useful when histologic studies were inconclusive in assigning a high degree of risk. Twice as many aneuploid carcinomas having nuclear grade 2 (intermediate risk) morphology proved to be metastatic. A similar relationship was found with deep myometrial invasion. A quantitative correlation between the DNA index and the risk of metastasis was found; a DNA index above 1.5 was a strong attribute of the metastatic group.