The application of genetic engineering techniques to the study of alle
rgens has considerably developed over the last ten years. At the prese
nt time, about one hundred allergens representative of the main allerg
enic agents have been cloned and produced, mostly in the form of fusio
n proteins. This approach has allowed identification of allergens whic
h had been purified by conventional methods and also characterization
and identification of new allergens. The classification of allergens i
nto families has therefore considerably advanced. The main consequence
is a better understanding of sensitizations and cross-allergies. Bank
s of recombinant allergenic peptides also represent an easier approach
to the study of B and T epitopes of allergens. Finally, several group
s have validated the use of recombinant allergens in laboratory diagno
sis and in skin tests.