Neuroleptic-induced acute akathisia (NIA) is a distressing condition and an important clinical problem because it is associated with treatment noncompliance and suicidal or impulsive behavior. Anticholinergics are among the treatment options; however, a review of the literature fails to identify a double-blind, randomized, placebo-controlled study of these medications in NIA. In a randomized, double-blind, placebo-controlled design, we studied the effectiveness of intramuscular biperiden (n = 15) or isotonic saline (n = 15) in the treatment of NIA diagnosed with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. Injections were repeated up to 3 times unless akathisia was completely treated (scored 0 for global akathisia with the Barnes Akathisia Rating Scale). Patients were assessed for akathisia, other movement disorders, and psychiatric symptoms at baseline and 3 times after the first injection at 2-hour intervals. Response was defined as at least a 2-point decline in the global akathisia score. The numbers of responders in the 2 groups were not significantly different (7 and 5 in the biperiden and placebo groups, respectively). The courses of individual items on the Barnes Akathisia Rating Scale were also similar. Our results suggest that intramuscular biperiden should not be considered as a first-line treatment of NIA.