HTLV-1-associated myelopathy (HAM), also known as tropical spastic paraparesis (TSP), is a chronic progressive demyelinating disease that affects the spinal cord and white matter of the central nervous system. The lifetime incidence of HAM in HTLV-1 carriers is estimated to be less than 5%. Typical time of onset is in the fourth decade of life, with a female-to-male rate of 2:1. Gait disturbance and weakness and stiffness of the lower limbs are common presenting signs and symptoms of HAM. Lower extremities are affected to a much greater degree than upper extremities. Spasticity may be moderate to severe, and lower back pain is common. As the disease progresses, bladder and bowel dysfunction can occur. Sensory involvement is generally mild and can result in a variable degree of sensory loss and dysesthesia. Results of magnetic resonance imaging may be normal, or the scans show atrophy of the spinal cord and nonspecific lesions in the brain. Immunologic evidence suggests that an immune mechanism may play a role in the development of HAM. There is no effective treatment for the myelopathy. Corticosteroids, and INF-gamma may produce transient responses. Danazol, an anabolic steroid, does not improve gait and bladder function. The value of zidovudine (anti-retroviral agent) in the treatment has not been defined yet.