This paper discusses an efficient method for handling time dependent boundary conditions with the DSS/2 differential equation solver. The method was evaluated by using it in the numerical solution of a diffusion problem. The proposed method is also particularly useful for boundary conditions in which only derivatives of the depend ent variables are involved. The method is based on transforming the boundary conditions at the interface to a set of algebraic equations which must be solved simultaneously at each integra tion step. Both algebraic and numerical solutions of this set of equations are discussed, and the relative merits of each one of these solutions are evaluated. The proposed method provides significant improvements in computation times and is capable of handling more complex boundary conditions as compared to other conventional methods.