An organic electroluminescent display device having an organic thin film transistor (OTFT) and a method of fabricating the same is disclosed. The display device can maintain an insulation property of a TFT and concurrently, ensure a sufficient capacitance by using an organic insulating layer for a gate insulating layer and using an inorganic insulating layer for a capacitor dielectric. In one embodiment, the organic electroluminescent display device includes a substrate having a capacitor region and a transistor region, a TFT formed in the transistor region of the substrate, and having a gate electrode, an organic semiconductor layer, a source electrode, and a drain electrode, a capacitor formed in the capacitor region of the substrate, and having a lower electrode and an upper electrode, and a display element connected to one of source/drain electrodes of the TFT. In one embodiment, a gate insulating layer formed below or on the gate electrode of the TFT includes at least an organic insulating layer, and a capacitor dielectric formed between the upper and lower electrodes of the capacitor includes an inorganic insulating layer.