Adherents of methods not based on scientific proof, especially the disciples of Huneke's "neural therapy", believe not only that foci represent local lesions, but also that they may cause remote effects. Therefore, in the opinion of these physicians, foci should be regarded as "fields of disturbance" with regulatory consequences, as described by Huneke and Pischinger. Thus when the diagnosis is in doubt, such "zones of interference" are searched for using function tests which are much in dispute. The most important of these "tests" are: electroacupuncture (Voll), the electro focus test (Glaser-Türk and Türk), neural therapy (Huneke) and thermoregulation (Schwamm). Moreover, it should be remembered that the adherents of the above-mentioned methods, on the basis of diagnoses worked out by the above techniques, will "cure" these foci, a serious matter. It is, therefore, recommended, that medical societies and medical and arbitration boards pay attention to this problem which also concerns unqualified practitioners. The results of such efforts should be published for the information of patients, doctors and insurance companies.