We present an error-tolerant SRAM design optimized for ultra-low standby power. Using SRAM cell optimization techniques, the maximum data retention voltage (DRV) of a 90nm 26kb SRAM module is reduced from 550mV to 220mV. A novel errortolerant architecture further reduces the minimum static-error-free VDD to 155mV. With a 100mV noise margin, a 255mV standby VDD effectively reduces the SRAM leakage power by 98% compared to the typical standby at 1V VDD.