Severe, uncontrolled spasticity resulting from spinal cord injury (SCI) and multiple sclerosis (MS) can have a profound effect on the patient's ability to function and thus, their quality of life. Spasticity can be dramatically reduced by the continuous infusion of baclofen into the lumbar subarachnoid space using a drug delivery system. The aim of this study was to explore the effect of reduced spasticity on quality of life using intrathecal baclofen therapy. Twenty-five patients with intractable spasticity treated with intrathecal baclofen participated in this prospective study. Spasticity was measured using the Ashworth and spasm scales. Quality of life was measured using the Ferrans and Powers Quality of Life Index (QLI) and the Sickness Impact Profile (SIP). The mean spasm score decreased significantly from 2.6 at baseline to 0.5 after one year (Friedman test; p = 0.000017). The mean Ashworth score decreased significantly from 3.78 at baseline to 1.48 after one year, (Friedman test; p = 0.00000014). Though total QLI scores were not significantly different when comparing baseline with one year, the SIP revealed significant changes in the total score as well as the physical and psychosocial subscales. It is likely the QLI did not demonstrate improvement in quality of life due to the emphasis of this tool on nonphysical domains. A qualitative analysis of two open-ended questions revealed positive statements about the change in quality of life when spasticity is well-controlled. Measuring changes in quality of life after specific interventions is a difficult task, requiring an accurate operational definition of the concept and valid instruments for measurement.