The current reference guideline about ethics in clinical trials is the Declaration of Helsinki of human rights in medical research. Three major principles are emphasised: respect of the patient to accept or not to participate in a trial, the constraints and the presumed risks must be acceptable for patients included in a study, and vulnerable subjects should not participate in studies. The investigator is responsible for obtaining a free and well-informed consent from patients before their inclusion in a study. Where possible, a new drug should always first be compared to placebo in order to prove its superiority. Else, a small-sized trial comparing a new drug versus a reference treatment can lead to an erroneous conclusion of absence of difference. Moreover, good results or improvement are obtained in at least 30% of cases with placebo, whatever the disease. The use of placebo is unethical in life-threatening diseases and when an effective proved drug exists. The use of placebo is ethical in severe diseases with no efficient drug, in some severe diseases even when an active reference treatment is available, and in all moderate and functional diseases. In order to detect flawed studies, most journals now ask for any manuscript submitted and reporting results of a randomised clinical trial to join a checklist in order to verify the quality of the trial. Finally, it remains the responsibility of the doctor to decide whether or not a protocol is ethical, to participate or not and to include patients or not.