A descriptive study was performed to investigate the epidemiology and clinical features of 50 patients with tropical spastic paraparesis (TSP) associated with HTLV-I infection acquired in Peru. Cases seen at two reference centers in Lima (Alexander von Humboldt Tropical Medicine Institute and Guillermo Almenara National Hospital) between August 1989 and December 1995 are reviewed. All patients had serologic evidence of infection with reactive ELISA tests for HTLV-I, confirmed by positive Western blot assays. The male-female ratio of cases was 1.0:1.78. The mean age at the time of diagnosis was 52.4 years (range: 29 to 73, SD:11.3). A considerable proportion of patients (68%) had lived in Andean regions: this basically due to their native places (48%) because only 8% of cases were referred from these regions. The mean duration of symptoms prior to diagnosis was 4.95 years (range 0.5–22years). The clinical features at diagnosis included progressive spastic paraparesis (100%) associated with sphincter disturbances (77.7%), paresthesia (61.1%) or lumbar pain (44%). The functional status of all patients was impaired at the time of evaluation: 44.1% walked unaided with a ‘scissors-like’ gait, 38% used assist devices for walking, 10% used wheelchairs and 8% were bedridden.