Mycinamicin I is a macrolide antibiotic produced by Micromonospora griseorubida sp. nov. Activity against gram-positive bacteria.The antibacterial activity of Mycinamicin I and Mycinamicin IV was stronger than that of other components, and was also stronger than that of erythromycin and lipopalcin A3. It also had antibacterial effect on some strains resistant to large ring vinegar antibiotics.