Seven cascades for simulated moving bed systems are developed for ternary separations with linear isotherms. The minimum desorbent-to-feed ratio, D/F, was determined for each cascade using the equilibrium model for 10 different separation problems. A cascade with 14 zones always had the lowest value of D/F, but other cascades could be simpler and/or have higher productivities. Rules of thumb are presented to determine reasonable cascades for more detailed simulation and detailed cost estimation. Detailed simulations showed that the cascades that the equilibrium model predicted to be best did give the best separations.