Rats were injected with chlorpromazine (CPZ), 21 mumoles/kg (7.5 mg/kg) i.p., and killed after different time intervals up to 24 h. Mass fragmentographic methods were used to determine the levels of CPZ, monodemethyl-chlorpromazine (nor1-CPZ) and 7-hydroxy-chlorpromazine (7-OH-CPZ) in brain and blood and dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-3-indoleacetic acid (5-HIAA) in the striatum. Significant correlations between the brain and blood concentrations of CPZ as well as its active metabolites and the levels of DOPAC and HVA were obtained at several time points. The similarity between the time curves for CPZ dominantly the unchanged drug in the brain which determines the acceleration of DA metabolism.