Aim. To identify pathologic features of the colonic mucosa in patients with chronic post-parasitic colitis. Methods. Under the observation were 80 patients aged 38-42 years (38 men and 42 women) 1.5-2 years after undergoing parasitic diseases (amebiasis, giardiasis, diphyllobothriasis). In 19 patients due to the presence of dyspeptic phenomena colon mucosa was evaluated by morphometric parameters using grid of Avtandilov. The control group consisted of 6 patients with adaptive norm, in which by complex evaluation (bacteriology, parasitology, endoscopic, histologic) the pathology has not been revealed. Biopsies of colon mucosa were fixed in 10% neutral formalin solution and embedded in paraffin. Histological sections were stained with 1% aqueous solution of Alcian blue, Mayer’s hematoxylin and eosin; for morphometric analysis of 24 objective indicators - azure II-eosin by Romanovsky, with eosin methylene blue and thionine by Nicolas. Results. It was found that the mucosa in chronic post-parasitic colitis in all cases different from the normal colonic mucosa by registered parameters: the amebiasis - in 50% of cases, giardiasis - in 54.1%, with difillobotriosis - in 70.8%. In post-difillobotriosis colitis the number of fibroblasts in the lamina propria was reduced. Post-lyambliotic colitis characterized by hypertrophy of the surface epithelium and a high mitotic activity of the epithelium of intestinal glands. Conclusion. After undergoing parasitic diseases, in the colon mucosa preserved histological changes corresponding to chronic ulcerative colitis; post-amebiasis chronic colitis characterized by catarrhal-haemorrhagic inflammation, chronic post-lyambliotic - catarrhal-follicular, post-difillobotriosis - catarrhal-haemorrhagic inflammation with high activity of the pathological process and moderate atrophy of the intestinal glands.