The endogenous electric field may provide an important signal for directional cell migration during cancer metastasis but the mechanism of cell electrotaxis is poorly understood. It was postulated that microtubules play a central role in the polarization and directional migration of several types of cells. In this paper we investigated the role of microtubules in electrotaxis of rat Walker carcinosarcoma WC256 cells. We found that colchicine-stimulated disassembly of microtubules caused the formation of blebs instead of lamellipodia at the front of about 45% of cells. Most of the remaining cells contracted and became rounded or transformed into non-polar cells. Depolymerization of microtubules in both subpopulations of cells reduced the directionality of cell migration to about 50% of the control, but bleb- forming cells migrated much more efficiently than lamellipodia-forming cells. The analysis of microtubules architecture in the presence of an endogenous electric field showed that there is no relationship between the direction of migration and the polarization of microtubules. These results suggest that microtubules are not indispensable for electrotaxis of WC256 cells, however they may improve the directionality of cell migration.