A new, very effective method of treating severe forms of acne (papuplopustular, conglobate, fulminating and tetrad) is the oral administration of 13-cis-retinoic acid. The results described by Peck et al. (1979) in 14 patients are demonstrated in detail in 18 patients. In the initial therapy 1 to 2 mg/kg body weight were administered daily for 12 weeks without any other local or systemic treatment. In the second phase of the study half the patients continued treatment with 0.5 mg/kg body weight 13-cis-retinoic acid, the other half remaining without any further therapy. All inflammatory lesions healed after 12-16 weeks, sebum production was largely reduced. 13-cis-retinoic acid represents a remarkable turn in the treatment of most severe acne.