The aim of this study was to evaluate the effects of intrathecal bacolfen (ITB) on patients with severe generalized dystonia. Eighty-six participants ranging in age from 3 to 42 years (median age 13 years) with generalized dystonia refractory to oral medications were offered treatment with ITB. Dystonia was associated with cerebral palsy in 71% of participants. Response to ITB was tested by continuous infusions in 72%, and by bolus injections in 17% of participants who had both dystonia and spasticity. Ninety-one percent of participants responded to the screening infusion and 93% to the bolus injections. Pumps were implanted in 77 participants. Dystonia scores at 3, 6, 12, and 24 months were significantly decreased (p<0.005) compared with baseline scores. Dystonia scores were significantly lower in those with intrathecal catheters positioned at T4, or higher than in those with catheters at T6 or lower (p=0.005). Ninety-two percent of participants implanted with a pump retained their responses to ITB during a median follow-up of 29 months. Patient questionnaires indicated that quality of life and ease of care improved in 86% and speech improved in 33%. Side effects of ITB occurred in 26% of participants. Surgical complications occurred in 38% and included CSF leaks, infections, and catheter problems. ITB is probably the treatment of choice for generalized dystonia if oral medications are ineffective.