&NA;Eighty‐six patients with acute psychotic exacerbations were treated with fixed dosage regimens of oral fluphenazine up to 10‐30 mg/day in randomized, double‐blind studies. Dystonic reactions occurred in 33.8% of the subjects at risk. Of these, 58% occurred by the third day, 88% by the fourth day, and 100% by the ninth day of treatment; most occurred later in the interdose interval. Significant predictors of dystonic reactions were higher fluphenazine mg/kg dosage and younger age. There was a trend toward a lower risk of dystonia in patients who received amobarbital sodium for agitation. Results are discussed in relation to possible mechanisms of neuroleptic‐induced dystonia.(J Clin Psychopharmacol 1990;10:389‐396)