Psoriasis vulgaris is a chronic dermatosis and is a widespread dematological disease. The most represented lesions are erythemato-squamous plaques with a tendency to cover large body areas with a great impairment of normal activities and a poor quality of life. Very often psoriasis is associated to other illnesses and the dermatologist has to be aware that comorbidities have to be taken in account for a successfull treatment of the disease. We report a case of a patient affected by severe psoriasis and HCV infection. He underwent a first treatment with etenarcept with good clinical results and no change of his viral load. When etenarcept became ineffective, he received efalizumab, with a good control of his dermatological condition and a reduction of the viral load.