Examination of a number of R-plasmid-containing bacterial isolates of animal origin has revealed the presence of a new aminoglycoside acetyltransferase (3-N) with a broad substrate range that includes all the disubstituted 2-deoxystreptamine antibiotics and also the novel monosubstituted antibiotic apramycin. Antibiotic derivatives acylated with hydroxyaminobutyric acid at the 1-amino position were not modified by the enzyme.