This paper presents a novel approach of palmprint authentication by matching the orientation code. In this approach, each point on a palmprint is assigned a orientation. And all point orientations of a palmprint constitute a palmprint orientation code (POC). Four directional templates with different directions are devised to extract the POC. The similarity of two POC is measured using their Hamming distance. This approach is tested on the public PolyU Palmprint Database and the experimental results demonstrate its effectiveness.