Amikacin, a new semisynthetic aminoglycoside antibiotic, was administered parenterally to 20 patients suffering from severe Gram-negative bacterial infections. The antibiotic was found to be highly effective in controlling infection. It was well tolerated and no signs of nephro- or otoxicity were observed. The few side-effects which were seen appeared to be dose-related. The recommended 12-hourly dosage regimen has also proved useful in medium- to long-term management of refractory pulmonary infections.