The cellular fatty acid composition of a group of gram-negative nonfermentative organisms designated group IVe was studied by gas-liquid chromatography. Strains of this group are isolated most frequently from urine and most closely resemble the Alcaligenes in conventional biochemical tests. On the basis of cellular fatty acids, however, we found these organisms to be strikingly different from Alcaligenes and other gram-negative species with similar phenotypic characteristics. The gas-liquid chromatography procedure offers an additional diagnostic test for rapid identification of unclassified bacteria like group IVe.