We report a case of allergy to cow's milk diagnosed in a 79-year-old woman, who had the habit of drinking large amounts of milk and other dairy products for several years. She had been an asthmatic since the age of 40. At age 65, she noticed a correlation between cheese and milk intake and onset of asthma and two episodes of shock, and she has been avoiding milk for the past 15 years. Positive skin prick tests for cow's milk proteins, grass pollens, and house dust mite were observed. Serum IgE levels were above 3,000 U/mL, with high molecular weight IgE detected by gel chromatography. RAST results confirmed the presence of sensitizations detected by skin prick tests. The patient never suffered from atopic eczema. This unusual case of food allergy with onset after the age of 40 may indicate that prolonged exposure to food antigens in predisposed individuals may lead to the development of allergy even in adult age, lasting for decades after partial elimination of the allergen from the diet.