The ability to secrete a potent protein-toxin called diphtheria toxin (DT) is of outstanding importance for the outcome of diphtheria epidemics. Rapid molecular-biological screening methods are shown that can improve the differentiation between toxinogenic and non-toxinogenic Corynebacterium diphtheriae strains. The recently reported infection with an endemic, putative toxinogenic Corynebacterium diphtheriae strain in Lower Saxony is discussed.