The pharmacokinetics of Amikacin (BB-K8) were determined after a single i.v. injection of 7.8 mg of the antibiotic/kg of body weight. It was administered to 10 patients with normal renal function and 19 patients with varying degrees of renal impairment. The elimination of Amikacin from plasma was seen to follow the course of an open two-compartment model system. From patients with normal renal function, values for the following pharmacokinetic parameters were obtained: alpha = 4.219 hr-1; beta = 0.292 hr-1; K12 = 2.218 hr-1; K21 = 0.859 hr-1; K13 = 1.432 hr-1; Vc = 3.125 1; Vp = 8.068 1 and Vdss = 11.193 1. As the relationship K12/K21 is greater than 1, it may be seen that there is a tendency for the antibiotic to accumulate in the peripheric compartment. Impaired renal function significantly diminishes the values recorded for alpha, beta, K12, K21, K13. Distribution volumes are significantly increased in patients with renal impairment. A linear relationship between the K13 of Amikacin and creatinine clearance is demonstrated. Adjustment of Amikacin dosage, according to the individual degree of renal impairment, may be obtained by spacing out the injections.