In the course of screening for antimycoplasmal antibiotics of actinomycetes origin, we found that strain AM-5344 isolated from a soil sample collected at Saiwai-cho, Chiba City, Japan, produces new antibiotics which have been designated cervinomycin A1 and A2 and were isolated from the culture filtrate of the strain. These antibiotics were active against anaerobic bacteria at low concentrations, such as Clostridium perfringens, Peptococcus prevolii and Bacteroides fragilis. The producing strain was classified as a new species of the genus Streptomyces and designated Streptomyces cervinus sp. nov. The present paper deals with the taxonomy of strain AM-5344 and the production, isolation, and biological and physicochemical properties of cervinomycin A1 and A2.