We report the additional pepstatins Bu, Pr and Ac (in which R is butyl, propionyl or acetyl, respectively) isolated from the culture broth of Streptomyces parvisporogenes strain No. MD494-A1 (isolated from a soil sample in Okusawa, Setagaya-ku, Tokyo, Japan). The strain belongs to a chromogenic type of streptomyces, forms whorls without spirals, has smooth spore surfaces, pale yellow to yellowish brown growth, white to yellowish gray aerial mycelium, hydrolyzes starch and protein moderately, utilizes glucose and inositol but not D-xylose, sucrose, etc. Pepstatins Bu, Pr and Ac were produced by rotary shaking culture in a medium containing glucose, starch, polypeptone, etc., with maximum production after 60-70 hours. They were purified via activated carbon adsorption, carbon column chromatography, Amberlite XAD-2 column chromatography, and silica gel column chromatography. Structural identification: hydrolysis yielded fatty acid components (methyl normal butyrate for Bu, methyl propionate for Pr, methyl acetate for Ac) and amino acids (alanine, valine, 4(s)-amino-3(s)-hydroxy-6-methylheptanoic acid in 1:2:2 molar ratio). Mass spectra confirmed molecular weights (Bu: m/e 685, Pr: m/e 671, Ac: m/e 657) and amino acid sequences similar to pepstatin A. Elemental analysis and melting points were provided. Inhibitory activity: they are almost equally active against pepsin and cathepsin D as pepstatins A, B, F and G; renin inhibitory activity increased with the number of carbon atoms in the fatty acid moiety.