An organic light emitting diode display that includes pixels having organic light emitting diodes and driving transistors for supplying a driving current to the respective organic light emitting diodes. Also included is a compensator for receiving a predetermined voltage applied to a gate electrode of the respective driving transistors, finding a threshold voltage, mobility, and a change of mobility of the driving transistors, and determining a compensation amount caused by an input image data signal while sinking a predetermined current to a path of a driving current to the organic light emitting diode through a data line connected to the pixels. Further included is a timing controller for receiving the compensation amount, correcting the input image data signal, and transmitting the corrected image data signal and a data driver for generating a data voltage based on the corrected image data signal, and supplying the data voltage to the pixels.