Thirteen nuclear and cellular morphometric variables were measured in 312 cases of colorectal adenocarcinoma. All variables, except nuclear shape factors, differed significantly (P < 0.001) between normal colorectal and tumor tissue. In adenocarcinomas, epithelial nuclei in well-differentiated mucosa tended to be elliptic, while those in poorly differentiated mucosa were more spheric. Increasing values of maximum nuclear and elliptic diameter were associated with progression from none to simple tubule configuration (P < 0.001), none to easily discerned nuclear polarity (P < 0.001), and expanding growth pattern (P < 0.001). Univariate survival analysis revealed that none of the morphometric variables was significantly related to patient survival. Multivariate regression analysis showed that no morphometric variable could add significantly to a model containing the variables of patient age, Dukes stage, and tumor differentiation. Morphometry may be useful in distinguishing malignant from normal tissue and degrees of differentiation, but it is of little prognostic value in colorectal adenocarcinoma.