Antibiotic A2315A is a new member of the virginiamycin family of antibiotics. Physical and chemical data indicate that it is related to ostreogrycin A. Structure II is proposed for A2315A. From a strain of Actinoplanes philippinensis COUCH, a new antibiotic has been isolated and designated A2315A. It is active mainly against Gram-positive organisms. Consideration of the physical and chemical data suggested that it might belong to the virginiamycin family of antibiotics. Closer scrutiny of its properties revealed a strong resemblance to ostreogrycin A (I). The latter is identical to virginiamycin M and several other antibiotics. The nomenclature in this area has been reviewed. We propose structure II for A2315A from results set forth below.