Three new antibiotics were isolated as minor components from the culture broth of Streptomyces mycarofaciens, and named as SF-837 A2, A3 and A4. They are basic macrolides and have the molecular formulae of C42H69NO15, C41H65NO15 and C42H67NO15, respectively. SF-837 A2 showed a UV maximum at 232mju, and gave on hydrolysis propionic acid and n-butyric acid, one mole each, suggesting to be a homologue of SF-837. SF-837 A3 and A4 exhibited a UV maximum at 280 mju, and liberated two moles of propionic acid and a pair of one propionic acid and one n-butyric acid in their respective hydrolyzates. Their antibacterial activities were analogous to that of SF-837. The physico-chemical characterization of three components established their novelties.