SummaryThe in vitro activity of dibekacin, a new aminoglycoside, has been compared to that of tobramycin and other antibiotics, against over 500 clinical isolates ofEnterobacteriaceae, Pseudomonasand staphylococci. The activity of dibekacin was similar to that of tobramycin. About 40 % of the gentamicinresistantEnterobacteriaceaeremained susceptible to dibekacin.A pharmacokinetic cross-over study of dibekacin and tobramycin was conducted in 6 healthy volunteers. After IV bolus injection and IM administration of single doses of 75 mg the pharmacokinetic parameters of both aminoglycosides appeared to be very similar: half-life times between 1.9 and 2.0 h, mean peak serum levels of 2.5 and 2.3 ug/ml after IM administration with a bio-availability of 100%, and a mean urinary recovery in 24 h between 72 % and 84 % of the dose.