Psoriasis is a relatively common disorder in children and can be triggered by an upper respiratory tract infection. The aim of this study was to compare the clinical features of psoriasis in children and adult. In addition, we evaluated the relationship between anti-streptolysin O (ASO) titers and the clinical features of psoriasis. A total of 30 childhood psoriasis patients and 30 adult psoriasis patients were evaluated. Childhood psoriasis had a facial predominance when compared with the adult psoriasis. The childhood psoriasis patients with high ASO titers had guttate psoriasis more frequently than patients with normal ASO titers. In children with plaque-type psoriasis, psoriasis area and severity index score was increased in the high ASO titer group than normal ASO titer group. In conclusion, if the children with psoriasis show increased ASO titer, the physician should pay attention to the worsening of the psoriasis. Furthermore, early treatment of streptococcal infections might be beneficial in childhood psoriasis.