The anodic polarographic behavior of aztreonam was studied in different supporting electrolytes. In 0.1 M hydrochloric acid, a single, well-defined, diffusion-controlled anodic wave was produced. The current-concentration relationship was found to be rectilinear over the ranges 2x10−5to 2x10−3M and 1x10−5to 1.6x10−1M in the direct current (DC) and differential pulse polarography (DPP) modes, respectively, with a minimum detectability of 4x10−6M using the latter technique. The mechanism of the electrode reaction was verified. The proposed method was applied successfully to the determination of aztreonam in pure form, in dosage forms and in biological fluids. L-arginine which is frequently co-formulated with aztreonam did not affect the polarographic signal of aztreonam to any significant extent.