The usefulness of clofazimine (CLO, CAS 2030-63-9) in the treatment of mycobacterial infections with special emphasis on treatment of leprosy is critically discussed. Skin discolouration which decreases compliance, placenta passage, excretion in mother's milk which endanger the embryo or baby respectively, saturation kinetics in absorption and difficulties to determine free drug concentration are severe problems. The observed antagonism in the combination of CLO with other drugs, especially with dapsone, is another argument against its application in the therapy of mycobacterial infections. In Germany CLO has not been approved by the Bundesgesundheitsamt.