The flow fields in bipolar plates have very important role in even distribution of reactant gases and removal of products from the reaction sites. An appropriate flow field pattern can significantly improve the efficiency and power of PEM fuel cells. In this paper a novel flow field pattern, called partially interdigitated, has been designed and its performance has been experimentally tested versus conventional serpentine ones. The results show 15% efficiency enhancement. The new design possesses partial obstacles placement along the channel, and enhances over rib convection effect. The obstacles increase the pressure of flow in serpentine; as a result it increases the mass transport of reactant and products to or from the catalyst layer and help to the removal of the water trapped in the porous area. The design increases the usefulness of MEA and optimizes application all the catalyst layer area. When compared to the interdigitated flow fields, it gives a much uniform pressure distribution over the electrode surfaces. The present work has recently been registered as a national patent in Iran by Kermani and Choghadi (2011).