The effects of feed concentration on the startup and steady-state behaviors of the simulated moving bed (SMB) process were studied with respect to various performance parameters (major product concentration, purity, productivity, eluent consumption, enrichment, and recovery). At the higher raffinate concentration of the feed, the concentration fronts of both components showed a longer migration distance and both concentration profiles were lowered. For the case of extract performance parameters, the startup periods grew longer as the raffinate concentration of the feed increased to 2.0 g/L and then slightly shortened at the higher concentration. On the other hand, the startup periods of raffinate performance parameters steadily became shorter as the raffinate concentration of the feed increased from 0.5 to 4.0 g/L. By drawing a comparison between the linear and nonlinear equilibrium designs, it is concluded that the nonlinear equilibrium design is advantageous from the standpoint of purity and productivity but is disadvantageous in terms of eluent consumption and enrichment.