Human T-Cell Leukaemia Virus (HTLV) has been found to be endemic in the Caribbean Islands. So-called spastic paraplegia of unknown origin, described in Martinique (named tropical spastic paraplegia in other countries) was found to be associated with signs of HTLV-l infection in 1984-1985. This association has since been found in non-tropical countries, particularly in Japan where HTLV-l is endemic. Numerous questions about the physiopathology of the neurological involvement and the systemic symptoms and signs remain unanswered. The identification of the retrovirus and of the diseases is only beginning.