Perphenazine is a typical antipsychotic drug. Chemically, it is classified as a piperazinyl phenothiazine. It has been in clinical use for decades.

Perphenazine is roughly five times as potent as chlorpromazine; thus perphenazine is considered a medium-potency antipsychotic.

It has an oral bioavailability of approximately 40% and a half-life of 8 to 12 hours (up to 20 hours), and is usually given in 2 or 3 divided doses each day. It is possible to give two-thirds of the daily dose at bedtime and one-third during breakfast to maximize hypnotic activity during the night and to minimize daytime sedation and hypotension without loss of therapeutic activity.

Perphenazine is used to treat psychosis (e.g. in schizophrenics) and the manic phases of bipolar disorder. Perphenazine effectively treats the positive symptoms of schizophrenia, such as hallucinations and delusions, but its effectiveness in treating the negative symptoms of schizophrenia, such as flattened affect and poverty of speech, is unclear. Earlier studies found the typical antipsychotics to be ineffective or poorly effective in the treatment of negative symptoms, but two recent, large-scale studies found no difference between perphenazine and the atypical antipsychotics.