An array substrate for an organic electroluminescent device includes a substrate; first and second gate electrodes; first and second gate insulating layers; first and second active layers; an interlayer insulating layer; first to fourth ohmic contact layers; first and second source electrodes; first and second drain electrodes; a data line connected to the first source electrode; a first power line connected to the second source electrode; a first passivation layer on the first and second source electrodes; a gate line contacting the first gate electrode; a second passivation layer on the gate line; a pixel electrode on the second passivation layer and contacting the second drain electrode; an organic luminescent layer on the pixel electrode; and a reference electrode on the organic luminescent layer, wherein portions of the pixel electrodes respectively contacting the organic luminescent layers in one pixel region and in another one pixel region have different heights from the substrate.