Growth hormone (GH) is a pluripotent hormone produced by the pituitary gland in teleosts as in other vertebrates. It plays important roles in the growth, development and metabolism of vertebrates. In this study, to characterize GH in fish and to better understand the potential applications of GH in fish culture, we used reverse transcription-ploymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) to obtain the full- length cDNA sequence encoding GH from the pituitary of darkbarbel catfish Pelteobagrus vachelli (P. vachelli) , a freshwater fish of high commercial value cultured in China. GH precursor cDNA (GenBank:GU395549) consists of 1 203 bp in size with an open-reading frame (ORF) encoding 200 amino acid, a 77 bp 5￠-untranslated region and a 523 bp 3￠-untranslated region. The four Cys residues are located at conserved positions (Cys71, Cys173, Cys190, Cys198), and one possible site for N-glycosylation (Asn-Xaa-Ser/Thr, motif) is present at Asn197 . Based on multi-sequence alignments and phylogenetic analysis, the P. vachelli GH precursor shared a higher degree of homology (averaged 95%) with other species of fish belonging to the Order Siluriformes, but lower levels of homology between P. vachelli and the mammalian (averaged 34%) and bird (averaged 41%). The above results reveal that GH is conserved during evolution and is suitable for phylogenetic relationship analysis of Siluriformes. By real-time quantitative PCR, tissue distribution profile showed that GH mRNA signals were all observed in pituitary, brain, muscle, liver, adipose tissue, stomach, spleen, ovary and testis. GH mRNA in pituitary was the most abundant and no significant GH mRNA expression was detected in kidney, heart, gill and intestines. The expression patterns of P. vachelli and previously studied animal GH suggest that GH through autocrine or paracrine pathway exerted its possible important local physiological function during development and growth of P. vachelli. These findings will contribute to the understanding of the evolution of GH and provide some basic information about the characterization of GH in P. vachelli.