Natural convection heat transfer from circular solid, hollow and hollow/perforated pin fin arrays with different geometry is studied numerically using ANSYS 16.0. The geometric dependence of heat transfer from heat sinks of solid, hollow and hollow/perforated fins with staggered arrangement, involved on a fixed area heated base plate is discussed. To solve governing equations (mass, momentum and energy), a SIMPLE code is developed using control volume approach. The second order upwind technique is used. The results were performed for a range of Rayleigh number, 9.3×106> Ra> 1.63×107. It presented that the performance of the solid fin heat sink is higher than the hollow ones and Nu for the hollow/perforated fin heat sink is higher than that for the solid fin heat sink. It is also investigated that hollow/perforated fin array with inner-to-outer diameter ratio (Di/Do=1/2) and perforation diameter (dp=6 mm) is the best sample giving the maximum performance and less amount of weight compared to the corresponding solid ones.