Hypoxanthine, xanthine and uric acid are purines present in extracellular fluids that can be used as metabolic markers, in evaluation of meat conservation and other applications. Voltammetric studies were performed in order to investigate the possibility of simultaneous determination of these compounds using carbon fiber ultramicroelectrodes (7 mum diameter). The studies revealed the possibility for performing such determinations with mean recoveries of 97.6% in mixtures of the three compounds at mumol L-1 level.