alpha-Lactalbumin represents one of the major allergens causing cow milk allergy. Few studies have clearly evaluated immunological relationships between immunoglobulin E (IgE) and immunoglobulin G (IgG)-binding epitopes of -lactalbumin. IgE- and IgG-binding epitopes were immunolabeled with individual sera from cow milk-allergic patients. Alanine scanning of immunodominant epitopes was used to identify the critical amino acid (aa). Our initial data revealed Val(8), Phe(9), Arg(10), Tyr(103), Leu(105), and His(107) were the critical aa for IgE-binding epitope. The critical aa of IgG-binding epitopes were Phe(9), Leu(15), Pro(24), Trp(26), and His(32). This study will provide necessary information to alter the cDNA to encode a protein capable of activating milk-specific T cells, but with reduced IgE- or IgG-binding capacity.