The recovery of precious metals from alkaline cyanide solution is accomplished effectively utilizing the well-established Merrill-Crowe process. Plant data from three silver operations were analyzed in terms of zinc efficiency, and mathematical models were generated with multiple regression techniques. Projections of the mathematical model are in good agreement with actual plant performance. The results of the regression analysis showed that the silver concentration in the feed is the dominant operating variable in determining zinc efficiency in Merrill-Crowe processing, and this is especially true for operations with low-pregnant grades. Pregnant grade and flow rate are the two operating variables which are beneficial to zinc efficiency. Increases in sodium cyanide concentration and zinc addition result in reduced zinc efficiency. Finally, the mathematical models indicate that modest economic improvement in Merrill-Crowe processing can be realized with relatively minor modifications to the circuits.