Intrathecal baclofen therapy has been used for several years, despite the fact that long-term gait modifications in ambulatory patients have not been thoroughly investigated. A 31-yr-old male patient affected by hereditary spastic paraparesis was evaluated clinically and by gait analysis. Evaluations were made before and at 6, 12, 16, and 24 mos after implantation. The patient showed a clear improvement in self-selected speed, step and stride length, knee and ankle kinematics, and ankle kinetics. Moreover, the response observed on self-selected speed is consistent with the intrathecal baclofen dose administered. To our knowledge, this is the first report of a long-term instrumental gait analysis assessment of a patient receiving intrathecal baclofen. Gait analysis could be a reliable and feasible assessment tool to evaluate ambulatory patients receiving intrathecal baclofen therapy over time and to help clinicians in determining exact dose requirements.