The effect of applying auxiliary pulses to the address electrode during the sustain period on the discharge characteristics of, an AC plasma display panel was investigated. When auxiliary pulses of 100 V and 250kHz were applied to the address elec ' trode during the sustain period, the maximum sustain voltage was found to decrease by 14%, while the minimum sustain voltage increased by 15% when compared to the case of a grounded address. It was also found that higher frequency auxiliary pulses resulted in a higher luminance in the sustain discharge. Consequently, the application of a pulse of 100V and 250kHz to the address electrode during the, sustain period improved the luminous efficiency by 12%.