A sensitive, specific and rapid determination of suprofen in human plasma and urine by fully automated high-performance liquid chromatography is described. Plasma or urine samples are directly injected into the liquid chromatograph, which consists of commonly available modules. Manual sample cleanup procedures as well as the addition of an internal standard are not needed. Using 20 microliter-aliquots, the detection limit is lower than 0.05 microgram/ml and the calibration ranges from 1.0 to 100 micrograms/ml are linear for both, spiked samples and references. The recovery is 99.2% for plasma and 99.7% for urine samples.