OBJECTIVE: To assess the presence of thrombospondin (TSP) in normal and colonic disease and correlate its presence to survival in colorectal cancers. MATERIALS AND METHODS: A specific antibody was used to stain paraffin-embedded sections of human colorectal disease (103 carcinomas, 10 inflammatory bowel disease (IBD), 10 diverticulosis and 10 normal). The stained sections were viewed by light microscopy and the degree of staining was quantified using computer-assisted image analysis system. RESULTS: Seventy-three percent of carcinomas, 30% of IBD and 80% of the diverticulosis specimens stained for TSP. None of the 'normal' specimens examined showed any staining. No significant correlation could be detected between TSP expression and survival in colorectal cancer patients. CONCLUSION: The presence of TSP in the colon is not specific and merely indicates the presence of a disease process.