Linear alkylbenzenesulfonate (LAS) is the most widely used synthetic surfactant. Environmental risk assessment of LAS requires quantitative information on the bioconcentration properties which, as yet, are unavailable. Here, we present compound- and isomer-specific bioconcentration data for n-(p-sulfophenyl)alkanes, the constituents of LAS, determined in flow-through experiments. BCF values ranged between 2 and 1000 L kg-1. We derived bioconcentration−hydrophobicity relationships and observed that bioconcentration factors as well as uptake rate constants increase with increasing log K OW (estimated) while the elimination rate constants do not vary with log K OW. In an attempt to account for the variability of the composition of LAS mixtures, we found the average length of the alkyl chain of the LAS mixture unsuitable for estimation of the bioconcentration potential. In contrast, an estimation based on the composition of the mixture of LAS and the bioconcentration factors of the individual constituents overpredicts measured values by less than a factor of 1.5. Using the composition of two LAS mixtures, one typical for LAS in detergents and one representing LAS in rivers, we calculated the respective bioconcentration potentials to be 91 and 22 L kg-1. This indicates that environmental processes decrease the bioconcentration potential of LAS mixtures.