Depression is one of the most costly illnesses in the United States today. While managed care often focuses on the costs of treatment, the costs of nontreatment are usually ignored. We have potent treatments that are highly successful, but depression is often undetected or undertreated where it appears most commonly-in the primary care setting. When comorbid with other medical problems, especially cardiovascular disease, depression greatly increases mortality, morbidity, and expense. Sophisticated pharmacoeconomic analyses can guide our cost/benefit studies, but the real cost savings and highest quality care will come by investing in educating primary care physicians regarding the recognition and treatment of psychiatric illness as it presents in their clinical practices.