Through exploiting the high homology of cereal crop genes, membranous cDNA microarrays containing 3 311 unique rice transcripts (including 1 639 endosperm-derived transcripts and 1 672 mature stem-derived transcripts) were used for monitoring the expression profiles of 1-leaf stage seedlings of 4 cereal crop species: rice, maize, sorghum and barley. After hybridizing with [α-33P| labeled probes, 73.6 % of the arrayed genes generated reliable signals in all of the four cercal crops. Further analysis revealed that among the arrayed genes, a higher percentage of the endosperm-derived transcripts (86.6 %) expressed than that of the mature stem-derived genes (60.9 %), indicating that most of the endosperm expressed genes functioned in young seedlings while considerable amount of mature stem tissue expressed genes did not express. These results also inferred that some genes might function only at certain developmental stages. By comparing the obtained profiles, 84 genes were identified constantly expressed in all me four cereal crops. Many housekeeping genes, such as polyubiquitin, ubiquitin conjugating enzyme and ribosomal proteins were included in this catalogue. The experiment also identified 14 rice seedling specifically expressed genes, including 3 biotic and abiotic stress induced genes and 1 apoptosis suppressor encoding gene Bax inhibitor-1. This investigation provided invaluable information for comparative genomics of gramineae members. Through exploiting the high homology of cereal crop genes, membranous cDNA microarrays containing 3 311 unique rice transcripts (including 1 639 endosperm-derived transcripts and 1 672 mature stem-derived transcripts) were used for monitoring the expression profiles of 1-leaf stage seedlings of After hybridizing with [α-33P | labeled probes, 73.6% of the arrayed genes generated reliable signals in all of the four cercal crops. Further analysis revealed that among the arrayed genes, a higher percentage of the endosperm-derived transcripts (86.6%) expressed than that of the mature stem-derived genes (60.9%), indicating that most of the endosperm expressed genes functioned in young seedlings while considerable amount of mature stem tissue expressed genes did not express. These results also inferred that some genes might function only at certain developmental stages. tantly expressed in all me four cereal crops. such as polyubiquitin, ubiquitin conjugating enzyme and ribosomal proteins were included in this catalog. The experiment also identified 14 rice seedling specifically expressed genes, including 3 biotic and abiotic stress induced genes and 1 This suppress provided encoding information for comparative genomics of gramineae members.