Introduction. Cow’s milk and dairy products are important sources of high-quality animal proteins, calcium, vitamins, and minerals. They are widely used in the diet of preschool and school-age children and contribute to the normal development and resilience of children against the effects of adverse external factors. However, cow’s milk can cause serious allergic reactions in children, even leading to anaphylaxis. Allergy to cow’s milk proteins is one of the common allergic reactions among preschool-age children. Through conducted research, patterns of the natural course of milk allergy over time have been established. In most cases, by the age of 5 years, children develop tolerance to cow’s milk proteins. However, some school-age children may retain heightened sensitivity to them. Sustaining such prolonged milk allergy in a school-age child requires identifying the cause and conducting in-depth examinations for each specific patient. In such cases, valuable information about elevated sensitivity to whole cow’s milk protein and its components is provided by molecular (component-based) diagnostics. This enables the identification of causally significant components (α-lactalbumin, β-lactoglobulin, bovine serum albumin) of milk protein for the purpose of rational diet therapy, considering cross-reactions with beef meat. The presented article summarizes and systematizes literary and proprietary data on allergy to cow’s milk proteins and its components, as well as to beef meat. Understanding the characteristics of allergy to cow’s milk proteins and its components, cross-reacting with beef, will help avoid serious consequences of irrational elimination diets.