Major depression in the elderly is often a relapsing, chronic illness with high risk for chronic invalidism, poor treatment compliance, and suicide. In most cases, maintenance treatment to prevent recurrence and to enhance the quality of life is thought to be indicated. We review recent data from our onging studies that support both the efficacy and the safety of pharmacotherapeutic and psychotherapeutic maintenance treatments. However, the challenges of conducting maintenance therapy research (particularly with a placebo control) with the elderly are many, involving such areas as recruitment, retention, compliance, choice of outcome measures, and informed consent. We discuss each of these challenges and our responses to them. Finally, we suggest that maintenance therapy trials should be extended in several directions: (a) long-term treatment of bipolar and delusional subtypes in the elderly, as well as depression associated with progressive neurodegenerative disorders such as Alzheimer's dementia; (b) assessment of the benefits and risks of long-term therapy with other than tricyclic and monoamine oxidase inhibitor antidepressant agents, such as selective serotonin reuptake inhibitors; and (c) development of models of long-term course, including the interaction of treatments with medical and psychosocial variables that can have a profound impact on illness onset and offset. These issues are illustrated with a discussion of a new protocol designed to test the acute and maintenance efficacy of antidepressant therapy for depressed patients with Alzheimer's disease.