Aim of the study. To investigate the frequency and clinical significance of detecting increased serum levels of IgE to food proteins, eosinophils (EOs) and mast cells (MCs) in colon biopsies in children with inflammatory bowel disease (IBD) in remission or with a low degree of activity.Methods and materials. 165 children with IBD and 81 children of the control group were examined. The level of serum sIgE to cow’s milk and wheat was determined. To detect cow’s milk protein allergy (CMPA), we used the questionnaire «Food Allergy» previously developed by us and validated on a group of patients with IBD. We performed the microscopy of histological preparations of the intestinal mucosa with counting of EOs and MCs.Results. The frequency increased sIgE levels to CMP in children with CD was higher than in children with UC, but there were no differences in the frequency of sensitization in the comparison group of children without allergies and IBD. An increased number of MCs was present in 37.0 % of IBD patients: 37.9 % of children with CD and 35.3 % of children with UC. Intestinal eosinophilia was observed in 15.2 % of children with IBD: 10.3 % with CD and 23.5 % with UC. A correlation was found between the average number of MCs in the biopsy specimen and the questionnaire score sums, in UC, as well as between the average number of EOs in the biopsy specimen and the questionnaire score sums and between the average number of MCs in the biopsy and the questionnaire score sums. In patients with CD, there is a correlation between the average number of MCs in the biopsy and the questionnaire score sums. Differences at the trend level were found between the average values of MCs in intestinal biopsy specimens in children with IBD with and without FA.Conclusion. The found correlation between the average number of MCs and EOs in the biopsy and the the questionnaire score sums shows that increased levels of intestinal MCs and EOs can be considered a diagnostic criterion for FA in patients with IBD with the presence of clinical data.