This study aims to investigate the effect of the alveolar ridge shape in the distribution of stress at the lower removable partial dentures supported by implants using a finite element method, with four models for a half mandible are designed with a free end saddle using an ANSYS program and Canine was abutment, where the remaining ridge is representing the four alveolar ridge shapes (horizontal and distal descending and concave and distal ascending), two removable partial dentures were designed for each model one supported by tooth and fibromucosa and another one supported by tooth and implant, it has been applied a load of 50 Newton on all models and has been studied stress equivalent for each model.