The quantum-confined Stark effect in a single InAs quantum dot has been studied in a novel device geometry, where both in-plane and perpendicular electric fields, E || and E ⊥ , can be applied. The shift in the photoluminescence energy from the exciton ground state of the dot has been studied as functions of applied bias voltages, V || and V ⊥ , and found to be quite anisotropic. Possible origins of the observed anisotropy are discussed.