This paper presents a theoretical model for prediction of undertow velocity profiles in the surf zone due to near-normally incident waves. The waves may be periodic or narrow-banded random waves, and the beach may be plane or barred. Both wave and surface roller models are based on simple energy balance equations. The undertow model consists of two-layer 2DH momentum equations, integrated above the wave trough level and over the entire depth. Coupled with a simple turbulent eddy viscosity model, analytical solutions are obtained for the vertical mean shear current profiles. Model predictions show excellent agreement with experimental observations which were not used in the model's development.