Peptide arrays have become versatile tools for high throughput screening assays in biomedical and pharmaceutical research. In this study, we constructed a peptide array that contained linear peptide fragments reported as IgE-binding epitopes for cow's milk allergy (CMA). Various peptides with different solubility in aqueous solutions were dissolved in the buffer solutions containing sodium dodecyl sulfate, and we achieved a consistent spotting of peptide solutions using a piezoelectric ceramic micropump. The IgE-binding patterns were successfully detected by observing the binding of Alexa 647-labeled anti-human IgE using sera from CMA patients. Our technique in this study will provide a potent capability for the development of a peptide array for mapping IgE-epitopes in milk proteins, and it will help researchers better understand the IgE-epitopes associated with the clinical outcome of CMA. (C) 2008, The Society for Biotechnology, Japan. All rights reserved.