Morphology of blood vessels in cancer of the larynx, which as other solid tumors has great neoangiogenic abilities, was studied on microcorrosion casts in SEM. Most evident changes of the endothelial patterns were seen on the casts of capillaries, venules, and veins. Capillaries, especially the newly formed, are the most numerous constituent of the vascular bed in all zones of cancer of the larynx. These vessels exhibit great morphological differentiation varying from the single, blind-ended pipes via relatively long hairpin loops spirally twisted in the long axis, to strongly spiralled and convoluted loops, resembling pseudoglomeruli. The newly formed capillaries deriving predominantly from the host's capillaries, venules, and veins have a embryonal character. It seems reasonable to presume that the neoangiogenesis process triggered by active influence of the tumor angiogenesis factor, is in principle, a repetition of the mechanism of the embryonal angiogenesis.