Objectives: Patients with human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) frequently experience voiding dysfunction. In patients with HAM/TSP, the major symptoms are gait disturbance and voiding dysfunction. However, the detailed natural course of voiding function and the management of their urination has not previously been investigated. We examined the correlation between voiding function and clinical features and evaluated the management of urination, in the patients with HAM/TSP. Patients and Methods: The voiding function of 47 patients (7 males, 40 females, aged 29-89 years, mean: 60.9 years) with HAM/TSP was analyzed retrospectively. All HAM/TSP patients are positive for HTLV-1. Patients were referred to a neurologist for analysis of bladder function. In the present study, we analyzed their clinical details, age at disease onset, voiding function and alterations in the management of their urination. Furthermore, we investigated the relationship between urological management and the clinical features of HAM/TSP. Results: Of the 47 patients, 20 (42.5%) were able to void with or without drug therapy. Thirty-four (72.3%) experienced clean intermittent self-catheterization (CIC), with 25 of these 34 continuing CIC, 7 changing to voiding and 2 changing to management with the Foley catheter. No relationship was noted between disruption of voiding function and either age or gender. However, significant inverse correlation was observed between the age at disease onset and the time to CIC (r = -0.77, P = 0.00001). Conclusions: These data suggest that the younger a patients is at HAM/TSP onset, the longer voiding function will be maintained. (C) 2003 Elsevier B.V. All rights reserved.