This study investigates the optimal pin fin array of variable cross section for a given fin material per unit base area. The effects of conduction, convection and radiation heat transfer is studied including the mutual irradiation between a fin and all other fins and the base. The finite difference method is used to solve the resulting nonlinear-integral-differential equations. The effect of parameters such as fin spacing, profile, and emissivity on the fin array effectiveness is studied and the results are presented in a graphical form convenient for parametric study and design analysis.