Abstract: Tubulin cofractionated with γ-aminobutyric acidA (GABAA) receptors upon affinity chromatography on Affigel 15 coupled to the benzodiazepine Ro 7-1986, and this cofractionation was not due to unspecific adsorption of tubulin to the column material. In addition, GABAA receptors not only bound to microtubules but also coassembled with added tubulin through three cycles of microtubule polymerization and depolymerization. These data indicate that GABAA receptors may be associated with the microtubule cytoskeleton in the brain. In an experiment designed to detect a protein that possibly could form a bridge between tubulin and the GABAA receptor, only a single protein band containing tubulin could be identified that was able to bind polymerized tubulin after sodium dodecyl sulfate-gel electrophoresis of affinity-purified GABAA receptors. These results are discussed with respect to a possible mechanism of association between GABAA receptors and microtubules.