In 159 patients with invasive squamous cell carcinoma of the uterine cervix, flow cytometric DNA patterns were related to eight histopathologic parameters according to a malignancy grading system, in which four of the parameters concern the tumor cell population and four concern the tumor-host relation. Each parameter was graded from 1 to 3 points. Flow cytometrically aneuploid values, contrasted to peridiploid ones, were more often found in specimens with immature, irregular nuclei, as well as in specimens with diffuse growth (p less than 0.05), obvious vascular invasion (p less than 0.05) or slight or no plasmolymphocytic response (p less than 0.05). For each histopathologic parameter, higher mean S-phase rates were found for the aggressive 3-point tumors than for the 1-point tumors. Tumors with total scores of 11-17 points were more often peridiploid than tumors with 18-22 points.