A young pregnant woman developed a persistent dystonic head tremor a few days after Rho (D) immune globulin administration; further deterioration occurred after a second administration of Rh(o) (D) immune globulin with the development of marked retrocollis. This persisted and she was treated 2 months later with a 5-day course of intravenous (1 g daily) methylprednisolone (IVMP) with resolution of her condition. We proceeded to treat similarly the next four patients with idiopathic cervical dystonia who were seen in our practice and who had current symptoms of less than 6 months duration. One also experienced persistent resolution and another had a marked, but transient, improvement after each of two separate courses of IVMP. The other two patients did not have improvement. This suggests a possible autoimmune pathogenesis for a limited subset of cervical dystonia. However, identifying which cases of recent-onset cervical dystonia will respond to IVMP therapy has yet to be determined.