A simple procedure for the determination of piromidic acid by square wave adsorptive stripping voltammetry (SW-AdSV) at a hanging mercury drop electrode has been developed. The variables affecting to accumulation process such as concentration of perchloric acid, accumulation potential and accumulation time have been optimised (0.025 mol L(-1), -0.25 V and 140 s, respectively) by using response surface methodology. A linear relationship between concentration of piromidic acid and peak intensity has been found in the range 2.22 x 10(-9) to 3.33 x 10(-8) mol L(-1). The detection limit (1.65 x 10(-9) mol L(-1)) has been calculated by the method proposed by Clayton et al. so that protection against both false positive and false negative errors is assured. The procedure was successfully applied to determine piromidic acid in spiked urine samples. The obtained recovery values were in the range 97.3-103.3% at different levels of concentration of piromidic acid.