αB-Crystallin, one of the small heat shock proteins, is constitutively expressed in lens as well as in nonlenticular tissues. It can function as a molecular chaperone for other lens crystallins and some other proteins. Its nonocular function is unknown although some reported one of them is related to cytoskeletal networks and/or components. In the present study, we demonstrate the association of αB-crystallin with tubulin. Imnninoprecipitation experiments using L6 myoblast cell lysate with anti-αB-crystallin antibody resulted in the coprecipitation of α-tubulin, which was apparently temperature-dependent. Further, purified αB-crystallin prevented the turbidity development of purified tubulin molecule at 37°C in vitro. Sucrose gradient centrifugation revealed that this chaperone activity was accompanied by the formation of large complex of αB-crystallin and tubulin dimer. These results indicate that one of the nonlenticular functions of αB-crystallin may be the protection of tubulin subunits of microtubules.