Treatment strategies against acute neuroleptic-induced akathisia (NIA) include anticholinergic (antimuscarinic) agents, dopamine agonists, GABAergic agents, beta-blockers, benzodiazepines, and serotonin antagonists. However, many patients who have acute akathisia fail to respond. In previous studies, mianserin and vitamin B6 were found to be effective in the treatment of acute akathisia. The purpose of this study was to compare the efficacy of B(6), mianserin and placebo in the treatment of acute NIA. Sixty schizophrenia and schizoaffective inpatients who have NIA were randomly divided to receive vitamin B(6) 1,200 mg/d, mianserin 15 mg/d, or placebo for 5 days, in a double-blind design. The Barnes Akathisia Rating Scale, Brief Psychiatric Rating Scale, and Clinical Global Impression were used to assess the severity of NIA and psychotic symptoms. The assessment was made at baseline and daily for the duration of the study. Compared with the placebo group, the vitamin B(6)-treated and mianserin-treated patients showed a significant improvement in the subjective (P < 0.0001), subjective distress (P < 0.0001), and global (P < 0.0001) subscales. The objective subscale did not show significant positive results (P = 0.056), but there was a trend toward symptom amelioration in both groups. A reduction of at least 2 points on the Barnes Akathisia Rating Scale global subscale was noted in the vitamin B(6) group (13/23, 56%) as well as in the mianserin groups (13/20, 65%), and in only one patient in the placebo group (1/17, 6%; P < 0.0005). Our results indicate that high doses of B(6) and a low dose of mianserin may be a useful addition to current treatments of NIA. The efficacy of vitamin B(6) and mianserin suggests that the pathophysiology of acute NIA is heterogeneous with the various subtypes of acute NIA responding differently to the various pharmacological approaches.