Abstract: Three ninhydrin-positive lipids of Streptomyces sioyaensis were found. These lipids were called substance A, B and C, tentatively. Study on the distribution of these lipids in Actinomycetales has shown that substance A was common in all of the strains tested, and that substance B was found in the limited strains. The substance C was characteristic only in Streptomyces sioyaensis.