Аннотация:We examine the ultrahigh-energy neutrino propagation in interstellar space in the Dirac and Majorana cases. Employing the two-neutrino mixing approximation and using the astrophysical constraints on neutrino magnetic moments, we show that both the avor and the spin oscillations of the Dirac and Majorana neutrinos exhibit qualitatively different behaviors in an interstellar magnetic eld for neutrino-energy values characteristic of, respectively, the cosmogenic neutrinos and well above the Greisen-Zatsepin-Kuz'min cuto.