Methyl and aminoalkyl esters of α-sulfonated fatty acids in the C9-C18range were subjected to aerobic biodegradation in a controlled nutrient medium in which sewage microorganisms were used as the inoculum and the test compound was the sole source of carbon and energy. The extent of biodegration increased with increasing alkyl chain length of the α-sulfo fatty acid and decreased with increasing substitution on the amino nitrogen and possibly with the increasing molecular weight of the substituent on the amino nitrogen atom. No connection was found between the degree of biodegradability and anti-microbial activity of the test compounds. Methyl α-sulfopalmitate was the compound of this study most inhibitory againstStaphylococcus aure