Since an increased incidence of occlusive vascular disease has been reported in psoriasis, serum levels of apolipoproteins AI AII and B were determined in 61 patients with the disease and compared with that of 34 healthy controls. No significant differences were found between the two groups. These findings suggest that the ocurrence of thromboembolic disorders in psoriasis is not related to altered levels of apolipoproteins AI, All, B in these patients.