Routine blood samples of 145 consecutive patients seen in the Los Angeles County Psychiatric Hospital Emergency Room during a 48-hour weekday period in June 1979 were examined for phencyclidine (PCP) using a sensitive and specific gas capillary gas chromatographic nitrogen detector (GC2-N) method. Of these 145 samples 63 (43.4%) were positive and PCP levels ranged 0.34 to 142.9 nanograms/ml (mean 14.6 ng/ml +/- 3.4 S.E.M.). An analysis of the records of these 63 patients revealed a wide variety of psychotic clinical pictures resembling mania, depression or schizophrenia with relatively few of the supposedly characteristic manifestations of PCP intoxication. Each of the 63 patients had at least one manifestation of toxic psychosis and/or acute delirium, in addition to the florid symptoms characteristic of functional states. PCP measurement, pharmacokinetics and the possible relationships of this intoxication to the psychiatric manifestations are discussed.