Aminoglycosides are one of the clinically relevant antibiotics. They kill bacteria by binding to bacterial 30S subunit of ribosome. Resistance to aminoglycosides occurs by three different mechanisms: 1. Production of an enzyme that modifies aminoglycosides, 2. Impaired entry of aminoglycoside into the cell by altering the OMP permeability, decreasing inner membrane transport, or active efflux, 3. The receptor protein on the 30S ribosomal subunit may be deleted or altered as a result of a mutation. By far, enzymatic modification has been the most important mechanism. In this review, the mechanisms of action and resistance, and the prevalence of resistance due to acquisition of enzymes are briefly described.