A study was performed of all patients who underwent either surgery or endoscopic polypectomy for colorectal cancer in Oxford between 1979 and 1983 to ascertain whether any changes had occurred in presentation, diagnosis, treatment or outcome since a previous study from the same centre undertaken between 1966 and 1971. The average number of patients treated annually had increased from 52.8 to 103.4. The growth of the population of the health district was 6.7%. A similar proportion (25%) continued to present as emergencies. There was an improvement in the proportion of cases presenting with Dukes' A and B lesions (54% vs 41%) (P < 0.001), and a decrease in the number of patients with extranodal disease (from 30.4% to 13.3%) (P < 0.001). Only 13.9% of patients underwent colonoscopy before surgery and 14 patients were treated by endoscopic removal alone. In a health district with a slowly growing population, the number of patients presenting with colorectal cancer had increased dramatically over a decade. Colonoscopy has so far made little impact on making an earlier diagnosis. The increase in colorectal cancer has important implications for resource allocation.