The usefulness of faecal occult blood tests is limited by their acceptability to patients. Standard tests require the collection of a stool sample which may inhibit compliance. Self-read tests which avoid this step have therefore been devised. Coloscreen Self-Test (CST) and Haemoccult, which may be regarded as the standard slide test, were offered to 450 consecutive patients attending surgical outpatient clinics with symptoms suggestive of lower gastrointestinal disease. Both tests were successfully completed by 383 patients. Although 262 (68 per cent) patients indicated that they preferred CST this was not reflected in the overall compliance to the two tests (CST 86 per cent, Haemoccult 90 per cent). CST gave a positive result in only eight out of 24 patients with a colorectal cancer (sensitivity = 33 per cent) compared with 13 out of 24 for Haemoccult (sensitivity = 54 per cent). CST had no advantage from increased compliance to outweigh its lower sensitivity.