In the field of medicine and health sciences, Delphi methods are applied mainly in the exploratory or evaluative phases of a research process. Explicit and implicit knowledge of respected experts from research and practice is systematically synthesized. Originally developed as a method for structuring a group communication process, Delphi techniques have been established in the health sector as a consensus method. The findings are used to improve the evidence and acceptance of planned interventions or necessary standards or guidelines and to increase the probability of successful implementation in practice. However, different variants of Delphi methods have been developed in recent years, which are systematically contrasted and reflected in this paper with regard to key epistemological and methodological research activities. Based on this overview, researchers should be enabled to select the most suitable Delphi technique for their own research questions and research endeavors.