The history, symptoms, diagnosis and treatment of phencyclidine hydrochloride (PCP) intoxication and the pharmacology of PCP are reviewed. Intoxication with low to moderate doses of PCP (5-20 mg) resembles an acute, confusional state generally lasting four to six hours. High doses (greater than 20 mg) may cause serious neurologic and cardiovascular complications and the patient is often comatose for several days. Treatment involves supportive psychological and medical measures. Evacuation of the stomach with activated charcoal and a saline cathartic may be indicated and succinylcholine chloride may ease intubation. Diazepam and chlorpromazine may be used to control the combative patient and the "PCP psychosis" patient, respectively. Antihypertensive agents are not usually needed, but diazoxide and hydralazine hydrochloride have been used to treat hypertensive crises. Diazepam and phenytoin have been used to treat seizures. Ion-trapping by continuous gastric suctioning and by urine acidification with ammonium chloride may increase clearance of PCP. Forced diuresis with furosemide in conjunction with acidification may further increase PCP clearance. Use of physostigmine is based on conjecture.