The aminoglycoside antibiotics are reviewed with regard to mechanism of action, bacterial resistance, antimicrobial spectrum, combinations with other agents, pharmacology, dosages in patients with normal and impaired renal function, adverse reactions, therapeutic use, prophylatic use and selection. Streptomycin is suggested in the therapy of tuberculosis, brucellosis, tularemia and yersinia infections; several of these require the coadministration of another agent. The choice between streptomycin and gentamicin for combination therapy of enterococcal endocarditis may be simplified by knowledge of the prevalence of high-level streptomycin-resistant strains in the hospital or by use of an in vitro screening test. Neomycin is the agent used orally in the treatment of hepatic encephalopathy. Paromomycin is indicated only for the treatment of amebic infections. The major difference among gentamicin, tobramycin and amikacin lies in the low but increasing prevalence of gram-negative bacilli which are resistant to gentamicin and tobramycin and susceptible to amikacin. In those institutions in which gentamicin-resistant strains are of concern, amikacin is the aminoglycoside of choice in high-risk patients until the infecting bacterium has been determined.