Polyoxyethylene (POE) alkylether-assimilating bacteria were isolated from soils by enrichment culture technique. Four isolated strains were all identified as genus Pseudomonas and their substrate specificities for some compounds related to nonionics were discussed. Moreover, assimilating ability of other species of standard genus Pseudomonas were also studied. The biodegradability of nonionic surfactants by these isolated and standard strains decreased in the following order, POE acyl ester, POE sorbitan fatty acid ester, POE alkyl ether and POE alkyl phenyl ether. Ester-type nonionics were first hydrolyzed at ester linkage in a relatively short time and fatty acid parts were gradually degraded. Polyether parts, however, were found to be hardly degraded within several days.