In 109 drunken male drivers from the area of Rostock the marker of alcohol abuse CDT was superior to the established laboratory parametres gammaglutamyltransferase (GGT) and mean cell volume (MCV) concerning the diagnostic efficiency. The prerequisite for the high diagnostic evidence of the CDT is the quantification of the minor band and the definition of standards of valuation by comparative studies with defined groups of probands (alcoholics, normal population). The combination of the 3 parametres CDT/GGT/MCV gave in 67% of the examined drunken drivers more or less strong hints at chronic alcohol abuse. The BAC of 1.6/1000 as a base for the decision to cause a medical-psychological examination (in case of "poison-resistance") turned out in this study to be an interchangeable, incomprehensible value. In about two thirds of the examined drunken drivers laboratory findings were pathological also in case of BAC below 1.6/1000. According to the experiences existing so far the parametres-combination CDT/GGT is unreservedly suitable as a screening procedure for the registration of potential or manifest alcoholics. Because the examinations may be performed from the usual blood samples for the BAC-detection these laboratory parametres really offer themselves for questions of traffic medicine. Further investigations are necessary.