NPC-related ESTs were selected from UniGene bank. According to nr and EST database BLAST results, BG231197 was found to be a sequence that represents a new gene. The EST contig does not have complete ORF. NAP1 gene cDNA was got from normal nasopharynx tissue cDNA by PCR through searching Human Genome Draft. The Northern blot analysis revealed one transcript (0.6 kb) in lymph node and trachea. GenBank Accession number of the gene is AY190326. The length of NAP1 gene cDNA is 573 bp, ORF is from 113 bp to 370 bp. NAP1 encodes a 9 700 u protein composed of 85 amino acids. The protein resembles to FDC-SP secreted by FDC (AF435080). Bioinformatics analysis suggested that the protein is a secreted protein. NAP1 gene is located at chromosome 4q13. Genome spans 9 179 bp, containing 5 exons and 4 introns. The difference of NAP1 expression between nasopharyngeal carcinoma (NPC) and nasopharynx(NP) tissues of 40 cases was tested by differential RT-PCR. Low expression occurred in 17 NPC cases. High expression occurred in 6 NPC cases. Expression difference did not occur in 17 NPC cases. In situ hybridization (ISH) and immunohistochemistry (IH) suggested that it express in dentritic cells of NP and NPC tissues. It is meaningful to do further studies on the reason of low expression in NPC tissue and the function of NAP1 gene.