At present, informed consent is essential before patients can participate in clinical trials. The fact that a doctor asks the patient for informed consent is an expression of respect for the patient's right to make decisions about his own body. The request is made in recognition of the fact that optimal treatment can only be ensured by means of clinically controlled trials. The need for regulation of research arose at the beginning of the present century when pharmacological development accelerated. The Nürenberg Declaration was elaborated after the second world war and, subsequently, the Helsinki Declarations I and II. In these, directives are established for clinical research and for the rights of participants. A number of conditions make it difficult to fulfill these intentions. It may be difficult to ensure that the patient has adequate basic knowledge. The patient may feel that he is in a state of dependence on the doctor which influences his possibility to choose freely. Confidence between doctor and patient may be undermined if the patient is requested to participate in randomization for choice of treatment. Doctors know too little about how valid information can be ensured.