Introduction: High Iron Diamine Alcian blue (HID-AB) is a well-established technique for demonstrating colonic acid mucins namely sulphomucins (brown-black) and sialomucins (blue). In certain colonic pathologies expression of sulphomucin, the predominant mucin in normal colonic epithelium is altered.Objective: To compare the changes in the pattern of mucin staining in, adenocarcinoma (AC), normal colonic epithelium, solitary rectal ulcer (SRU), transitional zone mucosa (TZ) (i.e.: normal non dysplastic mucosa adjacent to adenocarcinoma) and in ulcerative colitis (UC).Method: AC-21, normal colonic epithelium-30, SRU-23, TZ-20, UC-29 biopsies were stained with the HID-AB stain. Two investigators assessed the percentages of mucin staining by counting the number of cells staining for sulphomucin and sialomucin in an area of colonic epithelium measuring 1mm in length. The differences in these 5 categories were assessed for statistical significance using the one-way ANOVA test and a Post Hoc Comparison of the mean values was carried out to establish which groups were different.Results: ACs showed no sulphomucin or sialomucin staining while normal colonic epithelium showed nearly 100% sulphomucin staining.