We studied 154 patients presenting with significant colonic symptoms and subsequently diagnosed to have colorectal carcinoma. They were investigated by faecal occult blood tests, fibresigmoidoscopy, double contrast barium enema (DCBE) and colonoscopy. Faecal occult blood tests (Haemoccult) alone were positive in 26% of patients with Dukes' A, in 69% with Dukes' B and in 64% with Dukes' C lesions. DCBE alone identified the lesion in 32% of Dukes' A, 79% of Dukes' B and 81% of Dukes' C carcinomas. Fibresignoidoscopy diagnosed colorectal malignancy in 84% of patients with Dukes' A, 90% with Dukes' B and 81% with Dukes' C stage. A diagnostic yield of 88% for Dukes' A, 96% for Dukes' B and 100% for Dukes' C carcinomas was seen with colonoscopy. Detection rate for all stages of carcinoma was greater than 95% when fibresigmoidoscopy and DCBE were used together. Faecal occult blood tests and DCBE alone are inadequate in diagnosing early malignancy in symptomatic patients. Fibresigmoidoscopy and DCBE used in conjunction compare favourably with the technically difficult procedure of colonoscopy and should routinely be undertaken in these patients before malignancy can confidently be excluded.