The present study is concerned with upset forging of arbitrarily-shaped prismatic blocks which is characterized by three-dimensional deformation. From the proposed velocity field, the upper-bound load and deformed configuration are determined by minimizing the total power consumption with respect to some chosen parameters; such as the proposed method of analysis in this work can be used for prediction of forging load and deformation in upset forging of arbitrarily-shaped prismatic blocks. Closed-die forging of toothed disk is investigated using the slab method technique The tooth regions are approximated by prismatic rectangular sections. The velocity field comprising three-unit deformation regions is used. A constant frictional stress between work-piece and forging die is assumed. The average punch pressure normalized by the flow stress of the billet material is determined theoretically and compared with the present experimental results The experimental work is carried out on a commercial pure Aluminum (Al 1100) at room temperature The forging process is carried out using one die geometry without using any additional blocker dies. The theoretical predictions of forging pressures and deformation configurations are in good agreement with the experimental results. The experimental work proves that the analysis is good within approximately 36% of error according to many parameters.