We should ask about any therapy: (1) is it safe? and (2) is it effective? The best therapy is that which has the greatest chance to do good with the least chance to cause harm. Medical treatment is certainly safer than surgery, since (by my definition) surgery always involves a general anaesthetic, and morbidly obese patients are bad anaesthetic risks. Obesity also increases other surgical risks, so all published series of surgically-treated obese patients report some mortality. Surgeons will claim that surgery is much more effective than medical treatment, which has negligible success in morbid obesity. However all surgical bypass or banding procedures cause weight loss by restricting food intake, so if food intake can be equally restricted without surgery the results are just as good. In our experience jaw-wiring (which does not require a general anaesthetic) produces similar weight loss to gastroplasty. However the most difficult problem in morbid obesity is the maintenance of reduced weight many years after treatment. We have too few good long-term follow-up data after either medical or surgical treatment, but about half our patients treated with jaw-wiring and a waist cord maintain their weight loss on 3 years follow-up, zero mortality from the procedure. The results of surgical and medical treatments depend on the skill and care with which they are applied, and the way in which patients are selected. If patients are given treatment B if they are considered unsuitable for treatment A then the results from treatment A will be better.(ABSTRACT TRUNCATED AT 250 WORDS)