Aminoglycosides constitute one of the oldest classes of antimicrobials. Despite their relative toxicity, mainly nephrotoxicity and ototoxicity, aminoglycosides are valuable in current clinical practice. They are bactericidal agents with activity against aerobic gram-negative infections and against gram-positive cocci when added to a cell wall active antimicrobial-based regimen (e.g. betalactams). Aminoglycosides have a concentration-dependent bactericidal effect and a long post antibiotic effect. There is accumulating evidence to show that large, single, daily doses (or more correctly, extended interval dosing) of aminoglycosides is associated with less nephrotoxicity and ototoxicity and comparable, if not superior clinical outcomes than the same total dose administered in small, multiple doses. The efficacy and toxicity of aminoglycosides show a strong direct positive relationship with blood drug concentrations. A key strategy in minimizing toxicity and optimizing therapy is therapeutic drug monitoring. Key words: aminoglycosides - amikacin - gentamicin - therapeutic monitoring.