54The study aim was to assess the effect of corticosteroid (CS) therapy on the clinical and biological features of dermatomyositis (DM) or polymyositis (PM). Material and Methods7 adult patients with severe or refractory DM/PM diagnosed according to Bohan and Peter criteria, who also had involvement of bulbar muscles, respiratory insufficiency, myocardial involvement and/or total loss of ambulatory capacity, were included in study. The pulse-therapy consisted into daily pulses of 0.5 g methylprednisolone, 3 consecutive days/month, for three months. The following parameters were recorded upon presentation, and at one and three months of therapy respectively: muscle strength on a 6-steps scale, presence and type of cutaneous involvement, creatinkinase (CK) and C-reactive protein (CRP) levels.