The proposals contained in the White Paper 'Working for Patients' have been described as an attempt to introduce competition into a non-competitive situation. Together with the introduction of practice budgets for family practitioners, the granting of self-governing status to NHS hospitals is the principal mechanism by which this aim will be achieved. Very little is known about the effects of competition on the delivery of health care. Evidence from the United Kingdom is non-existent and from the United States of America is inadequate and contradictory. Yet, despite the inconclusive nature of this evidence, the U.K. Government is implementing the most radical reforms of the NHS since its inception without any systematic attempt to monitor the extent to which the reforms achieve the desired ends. In the absence of any systematic evaluation the responsibility for monitoring the effects of self-governing status will fall to the managers and public health specialists in the purchasing authorities. A variety of methods are described which would enable the reforms to be evaluated without holding back their implementation. No radical reform of the NHS can be expected to have an unambiguously beneficial impact on the delivery of health care. If the U.K. Government is genuine in its desire to improve health services, it should be prepared to subject its proposals to the sort of evaluation described in this paper.