Diffusion-weighted imaging (DWI) provides anatomic and functional information, and apparent diffusion coefficient (ADC) has been proposed as a valuable biomarker in liver diseases. Simultaneous multi-slice (SMS) technique allows for exciting and acquiring multiple slices at the same time, and thus reducing scan time, which has been recently proved to be feasible in liver imaging. Our study investigated the reproducibility and variability of liver ADC of SMS-DWI with different breathing schemes and different vendors. We found good reproducibility of liver ADC across different MR vendors in both breath-hold and free-breathing manner. However, liver ADC is less reproducible between different breathing schemes.