Sporeamicin A, a novel antibiotic, was isolated from the culture filtrate of an actinomycete. The producing organism, strain L53-18, was taxonomically assigned as a species of the genus Saccaropolyspora. The antibiotic was extracted with chloroform and was then purified by crystallization. It was obtained as colorless prisms from ethanolic solutions. Sporeamicin A exhibited a strong UV absorption peak at 276 nm. The molecular formula of sporeamicin A was determined to be C37H63NO12.