The objective of the studies reported in this paper was to determine the incidence as well as the final diagnostic outcome of rectal bleeding presenting in general practice. Because of the wide variety observed in incidence rates among 83 general practitioners (GPs) in the first study (A) an additional study (B) was undertaken. In study B with 10 GPs special efforts were made to maximize the catchment rate. The mean 'consultation incidence rate' was 7 per 1000 people per year. A follow-up period of at least 1 year was applied to establish the final diagnostic conclusion. Occurrence of colorectal cancer was found in 3% of patients with rectal bleeding. This may represent an overestimation of the prior probability since there was a selection in favour of patients with clinically relevant rectal bleeding. In about 90% of patients rectal bleeding was related to minor ailments or self-limiting disorders. Further study on predictive values of (combinations of) other signs and symptoms is necessary to develop clinical recommendations.