The authors studied in Káposztásmegyer belonging to the IVth district of Budapest the way of feeding and the frequency of skin, respiratory and gastrointestinal symptoms suggesting allergic disease in the first year of life of 405 infants born in 1993. It was analyzed whether the frequency of symptoms was related to the duration of breast feeding and the first introduction of cow's milk protein. In the 53 infants with symptoms the duration of breast feeding was significantly shorter (mean 12.5 weeks) than in the symptomless ones (20.2 weeks, p < 0.01). The first introduction of cow's milk was also significantly earlier in the infants with symptoms (mean 6.2 weeks) than in the healthy ones (11.8 weeks, p < 0.01). Cow's milk protein was more frequently introduced before the age of one months in infants with suspected cow's milk protein allergy (56%), than in the symptomless infants (34%, p < 0.01). It can be concluded that the shorter duration of breast feeding and the earlier exposure of cow's milk protein may increase the prevalence of allergic symptoms in infancy.