The cytoskeleton of Trypanosoma brucei has been analyzed by the high-resolution technique of quick-freeze deep-etch rotary-shadowing electron microscopy. The study provides detailed structural information on the subpellicular array of microtubules, the flagellum, and the interaction of these 2 major structures of the trypanosomal cytoskeleton with each other. The subpellicular microtubules closely interact both with the cell membrane and with each other. At the anterior tip of the cell they converge into a tightly closed structure, whereas at the posterior end the microtubular array remains open ended. The microtubular array is involved also in forming the opening of the flagellar pocket. The microtubular array interacts with the paraflagellar rod of the flagellum through a dense meshwork of fibers that are anchored on the microtubular surface with one end and within the paraflagellar rod structure with the other. The highly ordered, 3-dimensional network of the paraflagellar rod itself is connected tightly to the microtubular axoneme of the flagellum through a regular array of fleur-de-lis-shaped linking structures.