Medical futility concerns itself with decisions regarding treatments that are of minimal potential benefit to the patient. The concept of futility has evolved with the practice of medicine and consensus has been elusive. Presently, most typically, futility is conceptualized quantitatively as overwhelming improbability in the face of possibility, and qualitatively as an outcome that although achievable is overwhelmingly poor from the patient's perspective. Though frequently intermixed, futility and rationing are separate matters, with futility reflecting individual decisions taken at the bedside, whereas rationing represents decisions of publicly determined health policy. Objective, uniformly applicable guidelines regarding futility will likely be difficult to achieve and thus local efforts must be focused on implementing mechanisms to minimize and resolve inevitable disputes between patients, families, and caregivers.