An organic light emitting diode (OLED) display device and a method of fabricating the same capable of minimizing the number of process operations and a decrease in aperture ratio. The OLED display device includes a compensation circuit to compensate for a threshold voltage of a driving transistor. A pixel circuit of the OLED display device can be stably driven, can minimize a threshold voltage of a driving transistor using a minimized structure, and can increase an aperture ratio of the display device.