Pityriasis rubra pilaris (PRP) is an uncommon cutaneous disease with disorder of keratinisation. Up to now, systemic retinoids like acitretin or isotretinoin seem to be the most effective therapeutic agents. However, no large trials on this rare disease have been published and no standardised treatment has been established so far. Recently, single case reports demonstrate beneficial effects of alitretinoin (9-cis retinoic acid) in patients with PRP. We performed a retrospective observational analysis of type I adult-onset patients with PRP (n = 5) treated with systemic alitretinoin in our department. Alitretinoin was highly effective in the treatment of PRP in 4 of 5 cases. PASI score was reduced significantly in the alitretinoin responders. We assume that alitretinoin could serve as an additional effective systemic treatment option for type I adult-onset PRP.