The xenobiotic organic compounds linear alkylbenzene sulfonates (LAS) are among the most thoroughly investigated with respect to biodegradability. Previous studies have shown that LAS are relatively rapidly degraded under aerobic conditions, but only very slowly or not at all degraded under anaerobic conditions. In the present work, the degree of primary and ultimate biodegradation of LAS by consortia of aerobic microorganisms was examined. The quantification of primary biodegradation was conducted via analysis of the LAS content in the mixed liquor, which was based on microwave-assisted-extraction (MAE) followed by solid phase extraction with liquid chromatography coupled with a fluorescence detector (HPLC-FD). The ultimate biodegradability of LAS was examined by measuring both the disappearance of the test compound and the formation of carbon dioxide using the OECD method 301 B or the sulphate. It was found that the established enriched mixed microbial population was capable for complete mineralization of all LAS, as verified by the sulfate production as well as the application of the OECD method and the carbon mass balances carried out throughout the course of the conducted experiments. In particular, any intermediate compound formed during LAS biodegradation was rapidly decomposed, making any intermediate accumulation temporal.