Novel antibacterial antibiotics, kalimantacins A, B and C, have been isolated from the fermentation broth of Alcaligenes sp. YL-02632S. In this paper, the taxonomy of the producing strain, fermentation, isolation and biological activities of kalimantacins are reported. Kalimantacins inhibit the growth of Staphylococcus aureus and S. epidermidis including multiple-drug resistant strains.