A pixel circuit of an organic light emitting display includes a first transistor that transmits a data signal from a data line in response to a scan signal from a scan line; a first capacitor that stores the data signal received from the first transistor; a second transistor for threshold voltage compensation; a third transistor that transmits the threshold voltage of the second transistor; a fourth transistor that connects the gate and drain of the second transistor in a diode-connected configuration in response to a control signal from a control line; a second capacitor that stores the threshold voltage received through the third transistor; a fifth transistor that generates a driving current corresponding to a combined voltage of the first and the second capacitors due to the turned on third transistor; and an organic light emitting diode that emits light according to the driving current.