A carbon paste electrode modified with gold nanoparticle was prepared and used for low level acetazolamide (ACZ) determination in aqueous media. The measurement was made using differential pulse voltammetry. The influence of some experimental variables such as carbon paste composition, working solution pH, supporting electrolyte, scan rate, pulse amplitude and possible interferences were studied. The prepared and characterized modified carbon paste electrode demonstrated a linear current response over the concentration range between 0.01 mu M and 80.0 mu M ACZ, with a detection limit of 7.1 nM. The proposed sensor exhibited a high sensitivity and good selectivity and was applied for clinical evaluation of ACZ. (C) 2011 Elsevier B.V. All rights reserved.