The efficacy and safety of amikacin administered once-daily versus twice-daily was evaluated in adult patients with systemic infections. Patients over 23 years of age with suspected or documented systemic infections were randomly divided into two groups: one group received amikacin intravenously 15 mg/kg once-daily, and the other group received amikacin 15 mg/kg divided into 2 doses. The efficacy of both dosage regimens was very good with a satisfactory clinical response in 90.2% and 89%, respectively. The bacteriological cure rate was 82.2% and 76%, respectively. There were no significant differences between the 2 regimens as far as what efficacy and safety are concerned. Nephrotoxicity appeared in 2 patients of the first group and 3 patients of the second, but did not lead to discontinuation of amikacin. No significant differences between the regimens with regard to hearing loss or prodromal signs of ototoxicity. We concluded that amikacin administered once-daily appears to be as effective and safe as the twice-daily dosing. However, the once-daily administration is more convenient and less costly.