Oral allergy syndrome to soy milk is classified as a phenotype of pollen-food allergy syndrome (PFAS). As causative antigens, Gly m 4 (Bet v 1 homolog, 17 kD) and oleosin (23 kD), have been reported. In this study, we report two cases of PFAS to soy milk. Both cases showed positive reactions to soy milk in skin prick tests (SPT) and to Gly m 4 in specific serum immunoglobulin (Ig)E antibody. When we measured specific serum IgE antibody of soy-related proteins using a new laboratory testing method, microarray analysis, both cases showed a positive reaction for Bet v 1. One case was weakly positive for a soybean protein, beta-conglycinin. Other results for reactivity to soy, peanut, cross-reactive carbohydrate determinants and profilin were negative. Based on these results, we diagnosed the two cases as PFAS to Gly m 4. We also performed protein microarray analysis and found it useful as a screening test for immediate allergy, such as PFAS.