Seven strains of Enterobacteriaceae resistant to gentamicin obtained as representatives of the predominant resistance profiles in the clinical laboratories ofRafeidia andAl-Watani Hospitals in Nablus (Palestine) were included. Five strains showed a broad aminoglycoside resistance profile but contained no evidence of gentamicin acetylation, adenylation, or phosphorylation. Gentamicin uptake in two tested strains was significantly reduced, compared to that of gentamicin-sensitive E. coli (MIC, 0.5 lag/mL). These strains are likely resistant due to a relative reduction of the amount of gentamicin and other aminoglycosides entering the bacterial cell. Two strains showed evidence of adenyltransferase ANT(2")-I activity