Aminoglycosides remain a mainstay of antimicrobial therapy, especially for treatment of serious Gram-negative infections. Aminoglycosides represent cornerstone of antibiotic combination therapy and, despite their well-documented toxicity, continue to be used because of their excellent bactericidal efficacy and their limited tendency towards the development of resistance during therapy. Various factors, particularly their concentration-dependent bactericidal activity and prolonged post-antibiotic effect, indicate that aminoglycosides can be given effectively in a once-daily dosing regimen. Once-daily dosing has also been shown to reduce toxicity in animal studies. Although once-daily administration of amino-glycosides also has a number of practical advantages, questions remain concerning the indications that should be treated, the optimal peak and trough serum concentrations that should be attained, and the requirement for an initial loading dose. The present article examines the role of aminoglycosides in the treatment of serious infections and reviews the evidence presently available to answer questions on their appropriate clinical use.