The use of molecular techniques such as amino acid sequencing, DNA sequencing, molecular cloning, use of synthetic peptides, and monoclonal antibodies in the study of allergenic proteins has resulted in a large amount of information about a wide variety of allergens. The use of recombinant DNA techniques for the study of allergenicity of proteins is in many ways a preferred method to the traditional procedures, and recombinant allergens provide improved tools for allergen standardization, structural investigation, and T- and B-cell epitope identification. In the area of food allergy, molecular biologic advances are modest compared with those in the area of inhalant allergies. In a limited number of cases, recombinant allergens have been produced, but most of the molecular-level knowledge of food allergens has been gained using conventional molecular techniques such as amino acid sequencing and use of synthetic peptides. Much progress in the development of recombinant food allergens is expected in the near future.