Critical care resources in the United States are being rationed, that is, not all critical care expected to be beneficial is being provided to all patients who desire it. Although the extent of rationing is uncertain, it is an everyday occurrence in some hospitals and is likely to occur at least some of the time in many hospitals. Substantial evidence suggests that current rationing practices are highly subjective and perhaps inequitable. Critical care is widely believed to be beneficial to many patients, despite a striking dearth of supportive data. Since this type of care is being inequitably denied to some patients, hospitals should either adopt formal rationing guidelines or, alternatively, they should take clear steps to avoid rationing by altering the supply of or the demand for critical care. Reasonable arguments are presented in support of both approaches, as are suggestions for their implementation. (JAMA. 1989;261:2389-2395)