The twofold distinction between interventions into the germ line and interventions into somatic cells on the one hand and between the treatment of diseases and enhancement on the other hand resulted in the concept of somatic gene therapy. There is a nearly unanimous agreement that somatic gene therapy has a high-ranking moral objective and uses methods that extend current techniques for treating diseases in a morally acceptable way. In its experimental phase principles of research ethics as the autonomy and the informed consent of the patient or the test person, a fair selection of test persons and a careful weighing of risks and benefits have to be taken into account and several specific points have to be considered. Experimental somatic gene therapy requires a positive vote of a competent and independent ethics committee.