Recently, a more complete understanding of the pharmacodynamics of aminoglycosides has been recognized, indicating that this class of antibiotics exhibits both concentration-dependent bactericidal activity and a postantibiotic effect. This pharmacodynamic information, along with better knowledge of the mechanisms responsible for aminoglycoside toxicity, established the foundation for once-daily aminoglycoside dosing regimens. This new approach to aminoglycoside dosing appears to be safe, efficacious, and cost-effective, resulting in its increasing popularity in clinical practice.