Delavirdine is a novel non-nucleoside reverse transcriptase inhibitor for the treatment of HIV-1-infected patients. A simple and rapid high-performance liquid chromatographic method for the quantification of delavirdine in human plasma suitable for drug monitoring in patients is described. Sample pretreatment consists of protein precipitation with acetonitrile and subsequent evaporation of the extract to concentrate the analyte. The drug is separated from endogenous compounds by isocratic reversed-phase, high-performance liquid chromatography coupled with fluorescence detection. The optimal excitation and emission wavelengths are 300 and 425 nm, respectively. The method has been validated over the range of 50-50 000 ng/ml using only 200 microl of plasma samples. The assay is linear over this concentration range as indicated by the F-test for lack of fit. Within- and between-day precisions are less than 4.4% for all quality control samples. The lower limit of quanititation is 50 ng/ml. Recovery of delavirdine from human plasma is 93.8%. Delavirdine is stable under various conditions, for example 1 h at 60 degrees C and one week at 4 degrees C. This validated assay is suited for use in pharmacokinetic studies with delavirdine and can readily be implemented in the setting of a hospital laboratory for the monitoring of delavirdine concentrations.