Financial advisers who sell you insurance or mortgages are required by the rules to tell you how much commission they will earn as a result of your custom. But doctors who ask patients under their care to take part in a clinical trial are under no obligation to reveal how much they might earn as a result of their patients agreeing to take part in the trial. Can this be right?

Of course, the situation is not quite as simple as this. Selling insurance, one could argue, is not the same as inviting a patient to take part in a clinical trial. If the doctor was not reimbursed generously for his time then important clinical research would just not get done.1 The doctor can be trusted to put the best interests of the patient above personal gain, and therefore telling potential trial subjects how much the doctor will be paid is unnecessary. Do these arguments stand up to closer scrutiny? Or has the practice and scale of payments reached a point where it has become harmful to the conduct of good research?

Randomised clinical trials, often sponsored by pharmaceutical companies with a valid commercial as much as a genuinely scientific interest, are the only reliable way to generate good quality evidence of efficacy.2 Clinicians ideally should be in equipoise about the treatments being tested,3 and patients should give voluntary consent based on full disclosure …