In this paper, by modifying some techniques of [S.B. Norkin, Differential equations of the second order with retarded argument, Translations of Mathematical Monographs, Vol. 31, AMS, Providence, RI, 1972] and suggesting own approaches we …nd asymptotic formulas for the eigenvalues and eigenfunctions of boundary value problems of Sturm-Liouville type for the second order di¤erential equation with retarded argument.