Sporeamicins A (Antibiotic L53-18 A)1* and B2) are new 14-membered macrolide antibiotics isolated from Saccharopolyspora sp. L53-1 8. Their taxonomy of the producing culture, fermentation, isolation, structure determination and biological properties have been described in the preceding communications.2~5) During the search for other antibiotics in the culture filtrates of the sporeamicin-producing strain, we discovered a new minor component designated sporeamicin C (Fig. 1) which is described in this communication.