A pixel capable of displaying a uniform image in spite of process variation is disclosed. The pixel includes an organic light emitting diode display (OLED), a first transistor for controlling current that flows from a first power source to the OLED in response to a data signal, a second transistor connected between an nth (n is a natural number) scan line and a data line to supply the data signal on the data line to the first transistor when a scan signal is supplied to the nth scan line, a storage capacitor connected to the gate terminal of the first transistor to store the voltage corresponding to the data signal, and a third transistor formed to have a conductivity type different from the conductivity type of the first and/or second transistors and connected to the (n-1)th scan line so as to be turned on when the scan signal is supplied to the (n-1)th scan line. Therefore, it is possible to prevent leakage current from being generated due to process variation and to thus display an image with desired brightness.