In order to make evident an up to now only postulated generalized osteopathy in psoriatics in 24 patients with psoriasis and 24 patients with psoriatic arthritis the serum-calcium levels, the alkaline phosphatase in the serum and the excretion of hydroxyprolin in the urine were determined. Moreover, the bone bioptates of 25 patients with psoriatic arthritis and 10 patients with psoriasis were histologically examined and morphometrically measured, respectively. The examinations give evidence for the presence of a generalized "latent" osteopathy in the sense of an increased bone turnover rate without loss of bone volume (high turnover remodeling) in patients with psoriatic arthritis as well as in those with psoriasis without arthritis. As a common pathogenetically significant factor for dermatosis and osteopathy a latent vitamin D deficiency and a D-hormone resistance is discussed.