A high-performance liquid chromatographic method with UV absorbance was developed for the analysis of cefepime in human plasma and urine, and in dialysis fluid. Detection was performed at 280 nm. The assay procedure for cefepime in plasma involves the addition of an internal standard (cefpirome) followed by treatment of the samples with trichloracetic acid, acetonitrile and dichloromethane. To quantify cefepime in diluted urine (1:20) and in the dialysis fluid, samples spiked with the internal standard (cefpirome) were analysed using a column-switching technique. The HPLC column, Nucleosil C18, was equilibrated with an eluent mixture composed of acetonitrile-ammonium acetate (pH 4). Linear detector responses were observed for the calibration curve standards in the range 0.5 to 100 microg/ml, which spans what is currently thought to be the clinically relevant range for cefepime concentrations in body fluids. The limit of quantification was 0.5 microg/ml in the three matrices. Extraction recoveries proved to be more than 84%. Precision, expressed as %RSD, was in the range 1.5 to 9%. Accuracy ranged from 93 to 105%. This method was used to follow the time course of the concentration of cefepime in plasma, urine and dialysate outlet samples after a 10-min infusion period of 2 g of this drug in patients with acute renal failure undergoing hemodiafiltration.