The study involved 100 patients with inflammatory bowel disease: 65 patients with ulcerative colitis and 35 patients with Crohn's disease. The control group consisted of 50 participants. The mean age of the patients was 43.7±18.4 years. The diagnosis of UC or CD was established on the basis of clinical, laboratory, endoscopic, and histopathological results in accordance with the IBD diagnostic criteria. All participants underwent blood serum tests: IgA and IgG ASCA, p-ANCA by ELISA. Results. P-ANCA was significantly more common in the group of the patients with UC. 60 % of the patients tested positive for at least one antigen. The highest prevalence of p-ANCA was observed against lactoferrin, elastase, and proteinase 3. The occurrence of antibodies to ASCA was observed in 80 % of the patients with CD and in 15 % of the patients with UC. The proportion of the patients with a positive test result for IgA ASCA markers (72 %), IgG ASCA (57 %), and IgG / IgA ASCA (60 %) was significantly higher in the CD group than in the patients with UC and the control group (P<0.001). In the CD group, the proportion of the patients who tested positive for IgA ASCA was significantly higher in those after surgery compared to those who did not have surgical interventions. Conclusions. The most informative serological marker for UC verification used for differential diagnosis with CD are p-ANCA. The study revealed significantly more frequent localization of lesions within the colon and prevalence among young people in the patients with CD and with a positive ASCA result. A combination of ANCA and ASCA tests appears to be a good option for IBD laboratory diagnosis.