Although the benefits remain unproven, a considerable number of cancer patients use unconventional therapy, in many cases without the knowledge of the oncologist. At the oncological out-patient department of the women's clinic of the Justus-Liebig-University Giessen we conducted a survey of the various unconventional methods used. 38.8% (80/206) of the patients used unconventional therapies, mainly mistletoe extracts (50%), trace minerals (46%), megavitamins (39%), and enzymes (22%). The perceived etiology of cancer determined the choice for the various methods (p = 0.00074). Users of unconventional methods suffered significantly more from conventional therapy, had less faith in their doctors, and felt more nervous and emotionally unstable after the diagnosis of "cancer".