1-N-isoseryl derivatives of kanamycin A, kanamycin B and 3',4'-dideoxykanamycin B are now synthesized, which are new and useful compounds active against gram-negative and gram-positive bacteria and also against drug-resistant strains of these bacteria. The production of the 1-N-isoserylkanamycins is made by reacting isoserine with the 1-N-amino group of kanamycin with the functional amino group(s) being protected, following by removal of the amino-protecting groups and by chromatographic separation of the desired 1-N-isoserylation product.