The polyamines putrescine, spermidine and spermine are intimately associated with cellular growth and division. Previous studies of the polyamines and their rate limiting biosynthetic enzyme, ornithine decarboxylase, in psoriasis have shown significant changes compared with non-psoriatic skin. We have further studied cutaneous polyamines in patients with psoriasis and in normal subjects, epidermal shave biopsies were taken and assayed for ornithine decarboxylase activity and polyamine levels. Psoriasis lesions showed increased ornithine decarboxylase activity compared with uninvolved skin. The levels of ornithine decarboxylase activity in uninvolved psoriasis skin were also higher than in normals. There was increased putrescine in involved psoriasis compared with uninvolved and normal skin. Spermidine and spermine were increased in psoriasis skin and in uninvolved skin and compared with normals. The spermidine/spermine ratio was greatest in involved skin compared with uninvolved and normal. These results confirm abnormal polyamine metabolism in both the involved and uninvolved skin of psoriatics.