A patient's informed consent is required by the Nuremberg code, and its successors, before she can be entered into a clinical trial. However, concern has been expressed by both patients and professionals about the beneficial or detrimental effect on the patient of asking for her consent. We examine advantages and drawbacks of popular variations on consent, which might reduce the stress on patients at the point of illness. Both informed and uninformed responses to particular trials, and trials in general, are (...) discussed. The selection by doctors of patients, to whom entry to trials will be offered, is explored. (shrink)