By using the EST strategy for identifying novel members belonging to homologous gene families, a novel fulklength cDNA encoding a protein significantly homologous to UDP-Gal: N-acetylglucosamine beta-1, 4-galactosyltransferase (GalT) was isolated from a human testis cDNA library. A nucleotide sequence of 2 173 bp long was determined to contain an open reading frame of 1 032 nucleotides (344 amino acids). In view of the homology to memben of the galactosyltransferase gene family and especially the closest relationship toGallus gallus GalT type I (CK I), the predicted product of the novel cDNA was designated as human beta-1,4-galactosyltransferase homolog I (HumGT-H1). Its mRNA is present in different degrees in 16 tissues examined. Southern analysis of human genomic DNA revealed its locus on chromosome 3.