This chapter is a resume of a protocol which we have presented to the Medical Research Council of the United Kingdom for a multicentre trial to investigate the value of spinal fusion and spinal stabilisation for chronic low back pain. It has not yet been accepted by the MRC. This protocol represents over two years work by the authors, and we are grateful for the input provided by many spine surgeons and physiotherapists in the UK and abroad, as well a those in this city and elsewhere with expertise in the establishment of large multi-centre trials. Clinical trials are only able to answer a limited set of questions. This protocol is designed to satisfy the (very reasonable) demands of public health doctors and health purchasers for evidence that this type of intervention is effective in the management of chronic back pain. It is not designed to demonstrate that one surgical techniwue is better than another. These questions can only be tackled if this trial demonstrates a clear advantage of surgical treatment over non-surgical rehabilitation.