An analysis is made of the temperature and concentrational dependences of the magnetization and magnetic anisotropy constants of the series of compounds R2Fe14B (R = Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm), R2(Fe, Co)14B (R = Y, Gd) and RFe11Ti (R = Y, Dy, Ho, Er, Lu), taken from the results of measurements of the magnetic properties of single crystal specimens. It is shown that substitution of Fe by Co in compounds R2T14B does not result in growth of the magnetization of the subsystem of 3d-ions (Md); the experimental temperature dependences (Md(T) and of the rate-earth system (Mr(T) both in these compounds and in RFe11Ti can be described satisfactorily by a relation of the type (1-AT2)1/2 (Stoner law) and the theory of an 'anistropic' molecular field in the temperature range 0-0.7Tc, respectively. It is concluded that it is possible to interpret the magnetocrystalline anisotropy of both the ionic subsystems on the basis of the single-ion model with respect to the crystal field mechanism.