Alzheimer's disease may not yet be curable, but it is treatable. Two classes of drugs with differing mechanisms of action have received Food and Drug Administration approval for the treatment of Alzheimer's disease: the cholinesterase inhibitors and the N-methyl-D-aspartate receptor antagonist memantine (Ebixa, Lundbeck; Namenda, Forest Laboratories). Alzheimer's disease research directed at increasing the understanding of the underlying disease process has led to the identification of several other potential targets for drug development strategies. Due to the complexity of the disease, it is possible that combination therapy -- concomitant use of agents with nonoverlapping or even synergistic mechanisms of action -- may represent the best means available to enhance treatment effectiveness. This review evaluates the available data on combination therapy in Alzheimer's disease and provides an expert opinion on the use and implementation of combination therapy in clinical practice.