The risk factors for colon cancer recurrence following a curative intent surgery include the presence of metastatic disease, the tumor location and size, number of positive lymph nodes, the presence of adhesions, perforation, bowel obstruction, depth of invasion, histological grade, percentage of S-phase content, and cell kinetic profile. The DNA content of colon cancers in 20 Dukes' B2 patients in follow-up evaluation at our center, who relapsed, either locally or systemically following surgical treatment was measured by image analysis. The data were pair-matched for age, sex, tumor site, and grade with 20 Dukes' B2 patients who had no evidence of disease. Aneuploidy occurred in 16 (80%) patients with recurrence, as compared with only in 8 (40%) in the control group. Aneuploidy was associated with significantly higher tumor recurrence rate (P = 0.024) and shorter overall survival (P < 0.002). Our data may point out a possible indication for systemic adjuvant chemotherapy in Dukes' B2 colon cancer patients who have aneuploid tumors on image analysis. This warrants further investigation in a prospective controlled randomized study.