An organic light emitting display includes a current driving unit, an organic light emitting diode and a memory unit. The current driving unit is employed to provide a driving current according to a driving voltage generated therein. The organic light emitting diode generates a light output based on the driving current. The operation of the memory unit is controlled by a first auxiliary power voltage and a second auxiliary power voltage. When the first auxiliary power voltage is greater than the second auxiliary power voltage, the memory unit is enabled to perform a voltage retaining operation on the driving voltage. When the second auxiliary power voltage is greater than the first auxiliary power voltage, the memory unit is disabled for ceasing the voltage retaining operation.