The differences in the fatty acid composition of morphological variants of strain-destroyer of sodium dodecyl sulfate (SDS) Pseudomonas aeruginosa 1C are shown. Morphological variants differ by the degree of resistance against SDS and by the level of the destructive activity. The abnormally high level of fatty acids unsaturation is the particularity of their composition of the resistant smooth variant. The intermediate filamentous variant synthesizes the acid with 19 atoms of carbon absent in other variants. The rough variant has the least various spectrum of fatty acids. In the stationary phase the cells of the rough variant contain the largest number of cyclopropane acids.