Phylogenetic analysis of HTLV-I suggests three main subtypes, namely, cosmopolitan, Central African, and Australo-Melanesian. HTLV-I is endemic in KwaZulu-Natal, South Africa. However, sequence data on the local strains are limited to the LTR region. The env gene of the local strain was amplified and sequenced from the peripheral blood of five seropositive individuals. Four had HTLV-I-associated myelopathy and one had infective eczema. The sequence analysis of the env gene showed a greater then 99% homology of the local strains. They were closely related to the North American strains (99.3%), followed by the Japanese strains (98.3-98.9%). Phylogenetic studies linked the local strains to the cosmopolitan subtype. This study provides new sequence data on the env gene of the local HTLV-I strain.