In current discussions on ethical issues in psychotherapy, it is generally acknowledged that it is not possible that psychotherapist's value system does not influence the process of therapy and the professional relationship. The authors ask the following questions: how do therapists understand the standard of neutrality? What are the values identified by the therapists? How does the therapist's value system influence that of the client? How can the therapist involve his/her value system in order to achieve an improvement in therapy? What should the therapist do, when his/her value system differs from the client's? When does the therapist cross the ethical boundaries, trying to influence and change the value system of the client? Who is the guardian of the client's right to his/her value system not being undermined? The authors attempt to answer these questions analysing the literature concerning the ethical aspects of psychotherapy and several codes of ethics and conduct of the selected psychotherapists' associations.