Orosomucoid (ORM) types were studied by isoelectric focusing and immunoblotting in 175 psoriatic patients and 2,217 blood donor controls from the county of Västerbotten in northern Sweden. There was a significant difference between patients and controls with respect to the distribution of ORM types (p = 4 x 10(-4)). The ORM1 1 type showed an increased frequency among the psoriatic patients (p = 1 x 10(-4) with a relative risk of 1.82 (95% CI:1.34-2.48).