Objective To understand the gene characteristics of envelope region of human T lymphotropic virus type Ⅰ(HTLV Ⅰ)from Shantou region of China. Methods The gene of proviral envelope region of HTLV Ⅰ Shantou strain (named HTLV Ⅰ WHP)was amplified by PCR,using 4 designed primers,and then was sequenced,meanwhile it was compared with that of various HTLV Ⅰ representative strains from all around the world,and subsequently it was analyzed to construct its phylogenetic tree.Results The nucleotide sequence of complete envelope region of HTLV Ⅰ WHP provirus we have obtained was 1466 bp.There no deletion and insertion in the deducted amino acid sequence.The results of phylogenetic tree analysis showed that the HTLV Ⅰ WHP strain was most closed to some of the strains from Japan and Caribbean,and like the latter,belonged to the subtypea of cosmopolitan group.Conclusion The HTLV Ⅰ strains either from the coastal region of Southeast China or from Japan,Caribbean and so on have the common origin of evolution.