Aztreonam, the first licensed monobactam in the United States, is a β-lactam antimicrobial agent with a unique structure and in vitro spectrum of activity. The drug is active only against gram-negative aerobic bacteria in vitro, thus resembling the spectrum of aminoglycosides, but displays the safety profile typical of β-lactam agents. Due to these properties, aztreonam may prove useful in the therapy of various nosocomial infections. This review outlines the salient features of aztreonam and suggests areas of appropriate usage.