The prevalence of atopie diseases has markedly inereased in the past few decades, especially in industrialized countries. The etiology of atopie disease is multifactorial. The interplay of the individual genetic predisposition and various environmental and lifestyle factors seems to be crucial for the development of atopie disease. Epidemiolo-gical studies háve identified a number of risk factors for atopy and asthma. In this article we aim at providing a comprehensive review of known environmental factors associated with the development of atopy and asthma in childhood. The focus is on the most frequently associated risk factors such as early exposure to indoor allergens, environmental pollutants, tobacco smoke, early introduction of cow's milk proteins and solid foods and inereased intake of n-6 fatty polyunsaturated acids. More recently there is growing interest in the 'hygieně hypothesis' that underlines the role of protec-tive factors related to microbial exposure in infancy. Attendance at a day care center early in life, frequent episodes of viral infections of the upper respiratory tract, fecal-oral infections, endotoxin exposure during infancy and vaccination appears to offer protective effects against later development of atopy. Promoting effect of antibiotic use, and protective effect of breastfeeding remain controversial.

        Key words: atopy, asthma, environment, risk factors, protective factors