Baclofen, a gamma-aminobutyric acid receptorB, agonist, is used to reduce symptoms of spasticity (hyperreflexia, increases in muscle tone, involuntary muscle activity), but the adequate baclofen dose in each diseases is unclear. The aim of our study was to evaluate how dosage level improves the symptoms of spasticity. 25 weeks observational longitudinal follow up study assessed 16 patients who received intrathecal baclofen given by a programmable pump. Clinical efficacy was assessed by the Ashworth scale related with the dose of baclofen. Compared with pretreatment values, there was an improvement in clinical efficacy, but the baclofen dose needed for hereditary spastic paraplegia (HSP) was significantly smaller than that in other diseases. The result shows the importance of knowledge of the adequate baclofen dose in each disease in that baclofen causes some clinically significant adverse reactions.