The formation of the wake structures of a two-dimensional (2D) elliptic airfoil executing a simple harmonic heaving motion is investigated using Digital Particle Image Velocimetry (DPIV) technique. This work is motivated partly by the lack of experimental data on a 2D heaving elliptic airfoil and partly by the anomaly between the numerical results of Lewin and Haj-Hariri [Lewin, G. C. and Haj-Hariri, H., "Modelling thrust generation of a two-dimensional heaving airfoil in viscous flow," Journal of Fluid Mechanics, Vol. 492, 2003, pp. 339-362] and dye visualization results of Lai and Platzer [Lai, J. C. S and Platzer, M. F., "Jet Characteristics of a Plunging Airfoil", AIAA Journal, Vol. 37, No. 12, 1999, pp. 1529-1537]. The former study found that both the leading edge vortices (LEV) and the trailing edge vortices (TEV) contributed to the formation of the wake structures of a 2D heaving elliptic airfoil, whereas the latter study showed that only the TEV contributed to the wake structures of a heaving NACA 0012 airfoil. Possible reasons for the anomaly are provided.