Diffusion measurements by nuclear magnetic resonance (NMR) spectroscopy were used to investigate the host-guest association between beta-cyclodextrin (CD) and alkyltrimethylammonium bromide surfactants with different chain lengths, ranging from 6 up to 16 carbons. The scope and limitations of the method in the study of formation of inclusion complexes are discussed. The influences of the presence of CD in the micellization process have been studied, and the apparent critical micellar concentration and the self-diffusion coefficients of the species present in the systems have been calculated. The stoichiometries of the different complexes have been determined. Evidence for the formation of a 2:1 complex in the case Of C(16)TAB has been found.