1 The effects of p-chlorophenylalanine (PCPA) administered orally and intraperitoneally on rat brain 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content were compared. The depletion of brain 5-HT and 5-HIAA following PCPA (316 mg/kg) injected intraperitoneally every third day was not significantly different from that following the administration of PCPA (316 mg/kg) by stomach tube on eight consecutive days. 2 Rats tested for alcohol preference before, during and after treatment with PCPA on two intraperitoneal dose regimens (either 316 mg/kg then 100 mg/kg four days later or 316 mg/kg three times at intervals of three days) showed no reduction in voluntary alcohol consumption. 3 The results indicated that depletion of brain 5-HT and 5-HIAA is not responsible for the reduction of voluntary alcohol intake which has been reported to follow chronic oral administration of PCPA to the rat (Myers & Veale, 1968). The possibility of a learned aversion to alcohol due to an association with PCPA administration is discussed.