When using the peroxidase-sensitive guaiac fecal occult blood test, Hemoccult Sensa (HOS), dietary restrictions are recommended so as to reduce its false positivity from ingested peroxidases. As dietary restrictions could reduce compliance for annual retesting, we reexamined their need. HOS was given to 944 persons in an endoscopic screening/follow-up program. Only the first 403 received instructions regarding a low peroxidase-containing diet for three days before and during HOS collection. Development was delayed 3-14 days after HOS preparation, and there were no significant differences in duration before HOS development in examinees with or without colorectal neoplasia and having or not having a positive test. Of the 901 persons without endoscopic evidence of neoplasia, 377 had received and 524 had not received instructions on dietary restrictions. Their HOS positivity was 7.2% and 5.5%, respectively (P = 0.26). When using HOS, delaying development by 3-14 days allows breakdown of ingested peroxidases, so dietary restrictions are not needed in our population, which has a low red meat intake.