The magnetic anisotropy results of Ni₈₁Fe₁₉ multilayers, prepared by DC sputtering in ultra high vacuum, were described on the basis of existing models. It is shown that magnetoelastic anisotropy energies K_me of the Ni₈₁Fe₁₉/W₉₀Ti₁₀ multilayers which have fcc (111) perfectly flat interfaces can be expressed with biaxial modulus, magnetostriction and lattice mismatch. In the incoherent state, the residual strain gives rise to a magnetic anisotropy which is proportional to the reciprocal of the magnetic layer thickness. The influence of roughness would decrease the anisotropy contribution.