OBJECTIVE: To describe and discuss the epidemiologic characteristics and determinants of the use of complementary alternative medicine (CAM) from a European, particularly German, perspective. DATA SOURCES: An unrestricted literature search using the keywords alternative, allergy, complementary, epidemiology, and medicine was performed in PubMed (National Library of Medicine). In addition, background literature and the opinion of the author contributed to the article. STUDY SELECTION: European studies that provided data on the epidemiology of the use of CAM were selected and discussed in more detail. RESULTS: Approximately 30% of patients with allergies report experiences with CAM in Europe. In selected in-patient populations, the prevalence reaches 50%. Users of CAM tend to be younger women with a higher educational background. Furthermore, users and nonusers differ in terms of psychomedical characteristics, such as health locus of control or health-related quality of life. Although a larger number of different CAM modalities are provided, only a few techniques account for the majority of use (eg, acupuncture, homeopathy, herbalism, bioresonance, autologous blood injection). The use of CAM is associated with considerable costs, reaching an estimated amount of 0.9 billion Euro (approximately 1 billion US dollars) in Germany. CONCLUSIONS: CAM is widely used by the public to treat allergies. National peculiarities concerning the individual methods, providers, or reimbursement must be considered. The economic and public health implications should be discussed in context with the limited evidence of efficacy.