Cyclodextrins are cyclic oligosaccharides formed by a-(1,4) linked glucose units. The three first members are called a, b and g-cyclodextrin and they consist of 6, 7 and 8 glucose units, respectively. Cyclodextrins have the form of a truncated cone with the interior of the cone forming a hydrophobic cavity, while the outside of the cone is hydrophilic. Hence cyclodextrins are water soluble, although the solubility varies among the different members of the cyclodextrin family. As a consequence, they are often used to increase the solubility of sparingly soluble molecules in water. The literature on cyclodextrin is extensive [1]. Several issues pertaining to cyclodextrins are still not fully understood. One such issue deals with the possible self-association of cyclodextrins in water. Based on cryo-TEM work, it has been suggested that cyclodextrins form extensive aggregates in water [2]. Additional support for this suggestion has been published, see [1]. NMR, with its superior molecular resolution and sensitivity to molecular dynamics, has been extensively used to investigate self-association in surfactant and related systems. Here, we apply different NMR experiments to the issue of self-association of cyclodextrins. We will present 1H NMR derived self-diffusion coefficients, intensities and bandwidths for a, b and g-cyclodextrins over extended concentration regimes. Moreover, we have obtained deuterium labelled a, b and g-cyclodextrins and carried out a 2H NMR relaxation study, the results of which will also be analyzed and discussed. Taken together, we find no evidence in favor of extensive aggregation. The data do, however, support the formation of aggregates with limited aggregation numbers.