The effect of stimulation frequency for pallidal deep brain stimulation in five patients with either generalized or segmental dystonia was evaluated three to twelve months postoperatively via a randomized, double-blind paradigm. The quality of life and the severity of dystonic symptoms improved by approximately 60% and 43% respectively using a frequency of 130 Hz. Compared with 130 Hz a significant further clinical improvement was observed at frequencies of 180 and 250 Hz, which contrasted with a significant deterioration at lower frequencies (5, 50 Hz) compared to 130 Hz.