A cDNA library (2.1 x 10(6) pfu/mL) was constructed from the oral gland of Lampetra japonica. After random selection of clones for sequencing, 1 323 clones with inserts longer than 100 bp and with good chromato-grams were obtained. Using BlastX and BlastN programs, We found 653 ESTs (49.36%) that shared significant homology with known sequences in protein or nucleotide databases of NCBI, including 328 ESTs homologous to known sequences of Petromazonidae animals. These ESTs were classified into 11 different functional categories,the highest proportion of which was related to protein synthesis. Out of the 1323 ESTs, 162 non-redundant contigs were assembled from 547 sequences after alignment using software at the threshold of more than 90% homology over a minimum of 20 base pairs. There were eight full-length cDNAs with complete open reading frame. Further studies on the ESTs in the library may be helpful to elucidate the components of Lampetra japonica oral gland and to understand the function of those proteins at the molecular level.