Grain boundaries play an important role in determining the mechanical properties of metallic materials. The impedance of dislocation motion at the boundary results in a strengthening mechanism. In addition, dislocations can pile-up, be transmitted or be absorbed by the grain boundaries based on the local stress state and grain boundary character. In this study, a dislocation density based crystal plasticity finite element model is applied to incorporate the interaction between the dislocations and the grain boundaries, and a simulation is conducted on polycrystalline alpha iron deformed to 12% in uniaxial tension. The results indicate that the geometrically necessary dislocation density is generally higher near the grain boundary than within the grain interior. Taylor factor mismatch sometimes reveals strong localization effects near the grain boundaries.