This study performs an experimental study of pin fin heat sinks having circular, elliptic, and square cross-section. A total of twelve pin fin heat sinks having inline and staggered arrangements were made and tested. The effect of fin density on the heat transfer performance is examined. For inline arrangement, circular pin fin shows an appreciable influence of fin density whereas no effect of fin density is seen for square fin geometry. This is associated with the unique deflection flow pattern accompanied with the inline circular fin configuration. For the staggered arrangement, the heat transfer coefficient increases with the rise of fin density for all the three configurations. The elliptic pin fin shows the lowest pressure drops. For the same surface area at a fixed pumping power, the circular pin fin possesses the smallest thermal resistance for the inline arrangement. In the meantime, the circular pin fin slightly outperforms those other pin fin configuration under a staggered arrangement.