The case of a woman affected by an overlap syndrome systemic lupus erythematosus/polymyositis (PM), who presented with active myositis at the start of the pregnancy, is reported. Therapy with cyclosporin, corticosteroids, hydroxychloroquine and high-dose intravenous immunoglobulin induced a progressive remission of clinical and laboratory signs of myositis. At 33 weeks of gestation, after a premature pre-term rupture of membrane, a male child was delivered. Although premature, and small for gestational age, he had a normal growth, and did not show any clinical sign suggestive of immune deficiency. Lymphocyte phenotypical and functional studies, as well as response to vaccination, were also normal.