Plasma exchange (PE) and intravenous polyvalent immunoglobulins (IVIG) offer a new therapeutic approach to polymyositis (PM) and dermatomyositis (DM). Plasma exchange. The largest open study of PE was reported by Herson et al., in 57 patients with inflammatory myopathies (33 DM, 24 PM) who were resistant to classical treatments. The patients were described as having acute (< 6 mois, n = 38) or subacute or chronic (n = 19) disease. There were 41 females and 16 males with a mean age of 40.4 +/- 20.5 years. The mean number of PE was 14.8 +/- 9.2. The score of muscle function improved in 54% of the patients. A significant improvement in the muscle test was only seen in the acute forms, particularly in severe cases with impaired swallowing. The difference was not significant in the subacute and chronic forms. Intravenous immunoglobulins. Several recent publications have emphasized the importance of polyvalent IVIG in the treatment of inflammatory myopathies. In our experience, 30 patients (21 females, 9 males, mean age 44.5 +/- 18) with PM (n = 22) or DM (n = 8) were given IVIG after unsuccessful classical therapies including corticosteroids (n = 29), immunosuppressors (n = 28), PE (n = 8), total body irradiation (n = 1), and lymphopheresis (n = 1). Three to 6 monthly cures of 2 g/kg/cure polyvalent IVIG were given. Clinical improvement was significant as evaluated by muscle tests in 18 of the 30 patients. Global scores for the 30 patients rose from 44.2 +/- 12.7 to 65.3 +/- 17.9 points (for a theoretical maximum of 88 points) after the third cure (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)