Medication nonadherence for patients with chronic diseases is extremely common, affecting as many as 40% to 50% of patients who are prescribed medications for management of chronic conditions such as diabetes or hypertension. This nonadherence to prescribed treatment is thought to cause at least 100,000 preventable deaths and $100 billion in preventable medical costs per year. Despite this, the medical profession largely ignores medication nonadherence or sees it as a patient problem and not a physician or health system problem. Much of the literature on nonadherence focuses on barriers to adherence, with the assumption that appropriate adherence is the normal course of events and nonadherence is an aberration. This approach minimizes and oversimplifies the problem. It is not easy for humans to change their behavior, even for what many physicians see as a minor change such as taking prescription medications. Improving medication adherence has not been well studied, but a Cochrane review shows that multifactorial interventions are more effective. In at least one integrated health care system, Kaiser Permanente Northern California, a combination of approaches centered on the electronic health record has improved medication adherence rates to above 80%. Using similar elements would be feasible in other health care systems but would require motivation and planning. Effective change will not happen until key players decide to take on this challenge and reimbursement systems are changed to reward health systems that improve medication adherence and chronic disease control.