We report a case of dystonia with a partial deletion of the short arm (p) of chromosome 18 and androgen insensitivity. Neurologic findings in the 18p syndrome are reported to include mental retardation, seizures, incoordination, tremor, and chorea. A 15-year-old girl with a denovo 18p deletion [karyotype 46, XY, del (18)(p11.1)] developed progressive asymmetric dystonia. She had oromotor apraxia and partial expressive aphasia since childhood, and she was able to partially communicate through elementary sign language. At the age of 15 years, she developed subacute and progressive choreic movements of the right arm, severe dystonic posturing of the left arm, and spastic dystonia in both legs. Her response to parenteral or oral benzodiazepines, oral trihexyphenidyl, benztropine mesylate, baclofen, and L-dopa were brief and inadequate. The response to intrathecal baclofen has been sustained over 18 months. In all likelihood, the 18p deletion syndrome affecting this patient is significant in the pathogenesis of her acquired dystonia. Chronic intrathecal baclofen therapy via pump has been effective in this case and should be considered as a treatment modality in carefully selected patients with dystonia.