Undeclared allergens in processed products represent a major health problem for sensitized persons. Peanut flour and gluten are known as potent food allergens. The study was designed to evaluate with enzymeimmunoassay (ELISA) test kits the presence of gluten and peanut in Polish products. Hidden peanut contamination was detected in 4 of 34 (11.8%) processed foods (corn crisps, wafers, cereal bar and halva). 5 of 37 (13.5%) foodstuffs (cornflakes, corn crisps, bouillon cube, vegetable soup for infants, curry powder) contained undeclared gluten. The nutritional management of sensitized persons with food allergy requires new labeling regulations.