A high-performance liquid chromatographic method has been developed for the determination of dehydroevodiamine (DeHE), an active principle from Evodia fruit. Plasma was denatured with acetonitrile and centrifuged, the supernatant was separated and blown dry, and the residue was redissolved in water. Bile was acidified with perchloric acid and centrifuged to yield the supernatant. Aliquots were used for analysis. Elution was isocratic on a reversed-phase column with acetonitrile-water-phosphoric acid (64:35:0.8, v/v) adjusted to pH 3.5 as the mobile phase. Ultraviolet detection was at a wavelength of 367 nm. The detection limits were 2 ng/ml for plasma and 10 ng/ml for bile. The intra-day and inter-day variations were mostly below 10%.