We propose a method to quantify quinine in biological fluids using liquid chromatography. After alkalinisation, samples are extracted with a chloroform-isoamyl alcohol mixture; in the case of urinary samples, a preliminary enzymatic hydrolysis is performed. Extracts are analyzed by adsorption chromatography. A mobile phase composed of methanol-acetonitril-ammonia in used to elute. A post-column reaction with sulfuric acid allows a fluorimetric detection. With this method concentration as low as 0.05 mg/l can be measured. Variation coefficient is about 2.5 p. cent Quinine, its metabolites and dihydroquinine are well separated; thus it is a very useful method for pharmacokinetic and metabolic studies.