A microorganism, isolated from soil and designated Pseudomanas sp13, produced two kinds of rhamnolipid in the medium containing glucose as carbon source. There were both rhamnolipid contain L-rhamnose and β-hydroxydecanoic acid. Compound A and B elucted chloroform-methanol mixed solution of silicic acid column chromatography and recrystallized from a mixture of ether and n-hexane. Studies on the structure of these products reveled that compound A is L-rharnnopyranosyl-βhydroxydecanoyl-β-hydroxydecanoic acid and coumpound B is L-rhamnopyranosyl-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoic acid.