Gastrointestinal manifestation (GM) of food allergy (FA) in infants are non-specific, e.g.: frequent throwing up, colic, abdominal pain, vomiting, food refusal, which significantly complicates the differential diagnosis and selection of treatment direction.Materials and methods. 311 infants with atopic dermatitis symptoms were examined. 43 % of children (n=134) (studied group hereinafter) aged to 6 months had durable, resistant to conventional therapy pathological manifestations from the gastrointestinal tract. Laboratory tests were carried out for all of the children: determination of total venous blood serum levels of immunoglobulin, specific immunoglobulin E to cow's milk fractions (boiled milk, α – Lactalbumin, β – Lactalbumin, casein), to soya and goat's milk, eosinophil cationic protein levels (ECP). Guided by the ESPGHAN algorithm, diagnostic elimination diet was suggested to all of the infants during 4 weeks with the following lactose cow's milk (0.33% fat) provocative test for mother, in case of breast-feeding, or return to lactose-free formula, characterized by lower hydrolysis degree, in the case of artificial feeding. In the case of clinical symptoms restoration, the elimination diet was extended for three months, and then, after three months, provocative re-test was suggested. Laboratory parameters were monitored regularly 4 weeks and 3 months later, the additional ECP determination in blood serum was carried out in infants having positive provocative test.Research results. Positive clinical dynamics of symptoms was observed during the first week of the treatment in 127 infants, and it significantly correlated with ECP level reduction in blood serum. 51 children on the 4th week of observation, and 4 children on the 3rd month of observation had positive provocative test. The tendency to general and specific IgE decrease in relation to cow's milk fractions was slower (15–20 % on the 3rd month of treatment) and did not correlated with clinical symptoms dynamics.Conclusion. In infants, stable GM can be connected with allergic pathology. Direct and indirect provocation tests can be used by pediatricians for the allergy to cow's milk proteins diagnosis. The use of hypoallergenic nutrition formulas as basic and dairy-free diet for mother can significantly decrease GM of FA. Eosinophil cationic protein is advisable to use for the severity of the allergic process estimation in infantsDuring the first week of the treatment, ECP level decreased and it correlates with clinical symptoms dynamics.The tendency to general and specific IgE decrease in relation to cow's milk fractions was slower (15–20 % on the 3rd month of treatment) and does not correlate with clinical symptoms dynamics