The DNA content of 181 colorectal cancers wasinvestigated by flow cytometry on paraffin-embeddedspecimen.The relationship of flow cytometric DNApatterns of colorectal cancer to Dukes’s stage,histological type and grade,tumor size and patient’sprognosis were analysed.The DNA aneuploidcarcinomas were found in 53.04% of the patients(hypodiploid 22.10%,hyperdiploid 20.99%,polyploid9.94%).Diploidy was found in 46.96% of the patientswith colorectal cancer.The proportions of aneuploidywere significantly lower in the patients with Dukes’stage A(25.00%)and B(47.14%)than those withDukes’stage C(64.71%)and D(68.42%).Aneuploidfrequency was higher in the patients with poorly differ-entiated adenocarcinoma(84.62%),mucinousadenocarcinoma(62.50%)and tubular adeno-carcinoma(52.75%)than those with villousadenocarcinoma(22.86%).The proportion ofaneuploidy was significantly higher in the patients withpoorly differentiated tumor(71.79%)than in thosewith moderately(50.00%)and well differentiated tu-mors(44.83%).Five-year survival rate of the patientswith DNA aneuploid tumors was 33.80% comparedwith 66.67% of those with diploid tumors.Analysis ofCox regression revealed that DNA ploidy and Dukcs’stage significantly influenced the patient’s prognosis.Itis suggested that DNA ploidy might be an importantprognostic factor in colorectal cancer.