BB-K8 is a new derivative of kanamycin acylated with L(-)-γ-amino-α-hydroxybutyric acid at the C-1 amino group of the 2-deoxystreptamine moiety. The details of the synthesis, involving a selective acylation of kanamycin, as well as the structural proof for BB-K8 are described. BB-K8 has antibacterial activity generally equal to kanamycin against kanamycin-sensitive organisms and is also active against kanamycin- and/or gentamicin-resistant organisms, including Pseudomonas strains. It gives good protection against experimental infections in mice with both kanamycin-sensitive and resistant organisms. BB-K8 is not orally absorbed but gives high blood levels after par enter al administration and is excreted unchanged in the urine. BB-K8 is less toxic than kanamycin in terms of acute intravenous LD₅₀.