Amikacin, a semisynthetic analog of kanamycin, is very active against most gram-negative bacteria including gentamicin- and tobramycin-resistant strains. The effectiveness of amikacin in the treatment of serious gram-negative bacillary infections is well documented. Due to its resistance to inactivating enzymes, it is the aminoglycoside of choice for the treatment of known or suspected serious gram-negative infections caused by organisms resistant to gentamicin or tobramycin. Amikacin should be part of an empiric antibiotic regimen for the therapy of suspected sepsis in febrile, leukopenic immunocompromised hosts since it exhibits enhanced activity against the organisms most frequently encountered in this patient population. High response rates have been reported with the use of amikacin combined with beta-lactam antibiotics in immunocompromised or granulocytopenic patients. It exhibits impressive in vitro synergy against aminoglycoside-sensitive and -resistant organisms when used in combination with the new acylureidopenicillins and third-generation cephalosporins. Amikacin has the advantage of being the aminoglycoside least inactivated by the semisynthetic penicillins. Amikacin achieves high and predictable serum concentrations and has a favorable therapeutic index. Its potential for nephrotoxicity and ototoxicity is not significantly different than that encountered with gentamicin or tobramycin. Amikacin appears to be the preferred aminoglycoside for use at the present time because of its activity against gentamicin- and tobramycin-resistant organisms, its low resistance potential, its relative low degree of inactivation by the semisynthetic penicillins, and its superior pharmacokinetic profile.