Background:Inteleukin (IL)12 and IL23 are two main cytokines involved in the pathogenesis of immune-mediated disease. IL12 is produced by macrophages and B lymphocytes and mediates differentiation of Th1 lymphocytes, while IL23 is a pro-inflammatory cytokine essential for the differentiation of Th17 cells. Ustekinumab is a human monoclonal antibody directed against the p40 protein subunit shared by IL12 and IL23, therefore it blocks the signal transmission of both cytokines.Main observations:We present two cases and discuss the long-term efficacy of ustekinumab as a treatment of psoriasis in patients affected by autoimmune diseases, rheumatoid arthritis and Sjögren's syndrome, who presented with severe psoriasis after anti-TNF treatment. Conclusions:To the best of our knowledge, these are the first cases reported in the literature describing the long-term good efficacy of ustekinumab not only on paradoxical forms of psoriasis induced by anti-TNF-α drugs, but also on the articular involvement in a patient affected by RA and in a patient affected by Sjögren syndrome.