The magnetic anisotropy of the La0.75Sm0.25Mn 2Si2 compound, which has a layered ThCr2Si 2-type crystal structure, has been studied using a quasi-single-crystalline sample. It was found that the compound possesses a strong uniaxial magnetic anisotropy in both magnetically ordered and paramagnetic states. The magnetic anisotropy of the compound is mainly due to the Mn sublattice anisotropy. In the ferromagnetic state at 180K, the magnetization process is characterized by the magnetic anisotropy constant K1 = 6 × 106ergcm-3. In the paramagnetic state, a considerable anisotropy of paramagnetic Curie temperature Δp≈35K and an appreciable difference between values of the effective magnetic moment measured along the c-axis and in the basal plane, Δμeff≈0.4μB per formula unit, has been observed. The natural layered structure of the compound and partial unquenching of the Mn orbital momentum have been considered as possible reasons for the observed strong magnetic anisotropy.