With the prevalence of complementary and alternative medicine (CAM) increasing in western societies, questions of the ethical justification of these alternative health care approaches and practices have to be addressed. In order to evaluate philosophical reasoning on this subject, it is of paramount importance to identify and analyse possible arguments for the ethical justification of CAM considering contemporary biomedical ethics as well as more fundamental philosophical aspects. Moreover, it is vital to provide adequate analytical instruments for this task, such as (...) separating ‘CAM as belief system’, and ‘CAM as practice’, Findings show that beneficence and non-maleficence are central issues for an ethical justification of CAM as practice, while freedom of thought and religion are central to CAM as belief system. Many justification strategies have limitations and qualifications that have to be taken into account. Singularly descriptive premises in an argument often prove to be more problematic than universal ethical principles. Thus, non-ethical issues related to a general philosophical underpinning - e.g. epistemology, semantics, and ontology - are highly relevant for determining a justification strategy, especially when strong metaphysical assumptions are involved. Even if some values are shared with traditional biomedicine, axiological differences have to be considered as well. Further research should be done about specific CAM positions. These could be combined with applied qualitative social research methods. (shrink)