There is a lack of information in our country regarding allergies among infants. Objective: Measure the frequency of allergic reactions among children of an upper middle and upper socioeconomic group in Santiago, during their first year of life. Method: Chart information and telephone follow up every 3 months for a period of 12 months. Results: 7.2% of the children presented symptoms suggestive of allergies, and represented the "candidate group". At 12 months, all cases were reviewed, and 3.4% were thought to be probably allergic (48% of candidates). In all cases, the stimulus was thought to be cow's milk. Most frequent were digestive symptoms (88%), while three children had serious illness which included skin, respiratory and digestive symptoms. Treatment included maintenance of nursing when posible, and withdrawal of cow's milk from the diet, with success in all cases. Conclusion: The frequency of allergic type manifestations obtained by phone along the first year of life nearly doubledthenumber of diagnoses at 12 m of age. Figures obtained in the segment of population assessed were lower than those reported in other countries, mainly in Europe.