Proteomic approaches based on two-dimensional gel electrophoresis, mass spectrometry and database search are widely used to address questions about the development, physiology and quality of seeds. Identification of proteins is of great importance in proteomic analyses. For seed crops without full genome information, cross-species protein identification by mass spectrometry-driven sequence similarity search can be used. However, this approach is risky due to protein polymorphism between different species. Species-specific expressed sequence tag (EST) databases are an invaluable resource, which complements mass spectrometry data analysis for protein identification. Here, we illustrate a modified method of protein identification and characterization using species-specific EST databases and peptide mass fingerprinting with an example of protein identification. This method is reliable, supplements the existing methods, and improves the efficiency and accuracy of protein identification for seed crops for which complete genome information is not available.