The acute effect of intravenous injections of biperiden and clonazepam was investigated in 14 patients with various forms of dystonia (segmental dystonia, 2; generalized dystonia, 6; and Meige's syndrome, 6). Eleven patients had primary dystonia, and 3 patients had a secondary form of dystonia. Doses of 5 mg of biperiden reduced dystonia when evaluated by total scores, global scores, and subjective scores. Two patients had marked side effects in the form of dizziness. Doses of 1 mg of clonazepam significantly reduced total scores and subjective scores, but the reduction in global score was insignificant. No patient had marked side effects following injection with clonazepam. These results correspond with earlier investigations of the longterm effects of anticholinergics and benzodiazepines. It is concluded that in some cases, intravenous injections can be used as a test for evaluating both effects and side effects of antidystonic medication prior to the institution of oral treatment. Long-term intravenous treatment might be considered in individual cases.