Cry j 1 is one of the major allergens in Japanese cedar pollen. We attempt high throughput analysis and comprehensive identification of the linear IgE epitopes of Cry j 1. A series of overlapping synthetic Cry j 1 peptides chemically spotted on cellulose membrane was probed with sera from patients in Japan and United States, which were reactive to Cry j 1, and the reactivity of one of the detected sequences was confirmed by means of competitive ELISA using peptide as coated antigen. The peptide ³³¹NGNATPQLTKNA³⁴² (peptide 166) was detected by all three pooled sera used, and peptide ¹⁰³NGGPCVFIKRVS¹¹⁴ (peptide 52) was detected by two of the three pools of sera. In addition, several peptides reacted with one of the pooled sera. IgE binding to peptide 166-coated wells was inhibited by addition of peptide 166 for several individual patient sera, suggesting that peptide 166 is one of the linear epitopes of Cry j 1. Since patients in United States were suggested to be rarely sensitized with Japanese cedar, they were sensitized with the similar tree pollen allergens such as Cup s 1 and Jun a 1, and cross-reacted with Cry j 1. We have comprehensively investigated human IgE epitopes of Cry j 1 and succeeded in identifying a common linear epitope, ³³¹NGNATPQLTKNA³⁴².