The authors tested the possibilities of an apparatus for the assessment of tissue impedance -- DIACA LDN 200 -- in routine prevention of carcinoma of the uterine cervix. They found that by assessment of the impedance it is possible to differentiate normal squamous epithelium from calumnar epithelium and pathological epithelium. The latter two cannot be differentiated reliably by the apparatus. Therefore DIACA is not suited as a single method for the detection of precancerous conditions but in combination with colposcopy it may provide reliable services. In the discussion the authors reflect where to include most aptly the above method in the complex of prevention of carcinoma of the uterine cervix. Recently a new apparatus, DIACA LDN 200, was introduced on the market which can be used to measure tissue impedance. This apparatus proved useful in the detection of precancerous conditions and early carcinoma of the intestine (1, 2, 3). The basic idea links up with the work of Zwinger and Vrana (5, 6, 7) which some time ago aroused considerable attention but never was introduced in practice on a major scale. It is therefore of interest to test whether measurement of tissue impedance by means of this apparatus can be used in gynaecology and whether we may count on this method as a screening procedure in the prevention of carcinoma of the cervix.