In the case of three-dimensional Bloch elecrons, the electron motion along the field is not quantized by the field, and the most gaps of the transversal motion are smeared; therefore, the fractal structure of the "flux-energy" diagram disappears . Recently it was shown that the fractal structure appears in the "angle-energy" diagram for the tight-binding Hamiltonian (the strenghth of the field is fixed but the direction is varied); the result is published in

[1] M.Koshino, H.Aoki, K.Kuroki, S.Kagoshima, T.Osada: Hofstadter butterfly and integer quantum Hall effect in three dimensions,

[2] M..Koshino, H.Aoki, T.Osada, K.Kuroki, S.Kagoshima: Phase diagramm for the Hofstadter butterfly and integer quantum Hall effect in three dimensions,

In the talk, the results concerning the fractal structure of the "angle-energy" diagram for the Hamiltonian of an elecron in the presence of a uniform magnetic field and a periodic array of point scatterers will be reported. The results are obtained in collaboration with V.Demidov.