The field of asthma genetics has evolved in a markedly short time into a research field which potentially can provide a new level of understanding on the pathophysiology of the disease. There is consensus over a number of candidate genes that are likely to be important in the disease and also in chromosomal regions likely to contain other novel genes. It is, however, clear that there is no single major genetic risk factor for the development of asthma and the development of the disease in an individual will depend upon the interaction of a number of genes of moderate effect with environmental factors.