Differential pulse polarography (DPP) is proposed as a direct method for the quantitation of todralazine and acetazolamide in human serum. The method was applied to the determination of these drugs in human serum, after a liquid-liquid extraction process. This extraction process together with the use of the standard additions method is essential for the elimination of the matrix effect. The proposed method enables detection limits of 0.107 microgram ml-1 for acetazolamide and 0.111 microgram ml-1 for todralazine to be achieved at reduction potentials of -0.59 and -0.86 V, respectively, using Britton-Robinson buffer (pH 1.65) as the supporting electrolyte.