Consistent patterns of inflammatory bowel diseases (IBD), difficulties of diagnosis Crohn's disease and ulcerative colitis and peculiarities of their treatment have been studied on the basis of retrospective analysis of IBD patient case histories during 1995-2001 in the Department of Gastroenterology of Kaunas University of Medicine Hospital. Ulcerative colitis and Crohn's disease are chronic diseases that influence the quality of life, mortality and number of hospitalizations with their course varying in different countries. The number of cases hospitalized during the five years period was 273; 80% of which was ulcerative colitis, whereas the percentage of Crohn's disease was 20. The number of cases of ulcerative colitis increased every year while that of Crohn's disease started to grow in 2001. IBD is more common among males than females. It was at the expanse of young females that patients with Crohn's disease were statistically significantly younger than those with ulcerative colitis. Proctosigmoiditis (45.9%) and left colitis (27.1%) are common predominants in ulcerative colitis, while ileocolitis (63.6%) predominates in Crohn's disease. Ulcerative colitis correlates with stool frequency and extent of disease. Course of IBD is rather grave and relapses are quite frequent.