The microviscosities of the self-assemblies formed by sodium N-(11-acrylamido-undecanoyl)-aminoacidate, and N-(4-n-dodecyloxybenzoyl)-aminoacidate surfactants were estimated by fluorescence anisotropy measurements using 1,6-diphenyl-1,3,5-hexatriene as probe molecule. The self-assemblies have high microviscosities in consistence with their bilayer membrane structures. In order to test the validity of the method, the results have been compared with those of micelle forming surfactants, sodium dodecylsulfate, dodecyltrimethylammonium bromide, cetyltrymethylammonium bromide, and Triton X-100 for which the microviscosity data are available in the literature. (c) 2005 Elsevier B.V. All rights reserved.