Dark field microscopy [also called live blood analysis (LBA) or peripheral blood assessment] according to Enderlein claims to be able to detect forthcoming or early cancer through minute abnormalities in the blood. In Germany and the USA this method is used by an increasing number of physicians and health practitioners. In this study blood samples were drawn for dark field mircroscopy in 110 patients. A health practitioner with several years of training in the field carried out the examinations without prior information about the patients. Out of 12 patients with present tumour metastasis three were correctly indentified. The study concludes that dark field microscopy does not seem to reliably detect the presence of cancer and that clinical use of the method can therefore not be recommended until future studies are conducted. Forsch Komplementarmed Klass Naturheilkd. (June 2005)