To clone the full length cDNA sequence of a novel expression sequence tag ST55 (GenBank Accession No. BI121646) from human umbilical vein endothelial cells stimulated by lipopolysaccharide, rapid amplification of cDNA ends (RACE) was used to extend the 3′and 5′ends of ST55 to obtain the full length cDNA sequence according to the known ST55 sequence. The cDNA was identified by Northern blot and analyzed with bioinformatics. A novel human full length cDNA was cloned and named endothelial overexpressed lipopolysaccharide associated factor 1( EOLA1 ) (GenBank Accession No. AY074889). This gene was located at chromosomal Xq27.3 and encodes a protein EOLA1 composed of 158 amino acids. Our data show that EOLA1 is a novel human gene associated with activated endothelial cells, and may play a role in intercellular signal transduction.