Existing immunoglobulin (Ig) tests only give a limited picture of the immunological response to food antigens. Furthermore, existing tests require large volumes of sample, over a limited number of foods, are not amenable to a high sample through-put system and the results are limited to normally just one immunoglobulin class. In order to investigate the global immune response towards food products we have developed the "all diet" microarray concept. The "all-diet food protein microarray contains extracts of over 400 food ingredients that cover most of the food products found in the UK. Using this system we have retrospectively determined food specific IgE, IgA, IgG and IgM from 17 well characterized sera. The results were analyzed by multivariate techniques and parametric methods. The proof-of-concept of the ''all diet microarray to investigate the relationships between food antigen specificity and multiple Ig type was demonstrated here. The novelity of this protein microarray is the use of arrayed food samples sequentially extracted with detergent and chaotropic agents. The array system possesses many advantages over traditional systems such as requirement of low sample volume, high sensitivity and a global view of the immune response. Notwithstanding these potential advantages to clinical practices, these benefits remain yet to be demonstrated. The development of the technique will allow further expansion into areas of research such as conjugation of the microarray with sensitized human basophils and also immunoglobulin binding to extracts of parasites.