Objective: To present a rare case of breast cancer associated with both inflammatory muscle disease and liver disease as a paraneoplastic syndrome. Clinical Presentation and Intervention: A woman with breast cancer presented with elevated liver enzymes and progressive proximal muscle weakness. Liver biopsy was consistent with hepatitis and muscle biopsy revealed myositis. The start of corticosteroid therapy was followed by relief of the myopathic symptoms and regression of hepatitis histopathologically. Conclusion: A case of polymyositis and hepatitis associated with breast cancer and their flare-up with recurrence of malignancy is presented. In this case, the temporal relation with malignancy following its concurrent remission and relapse suggests a paraneoplastic mechanism. Copyright (C) 2004 S. Karger AG, Basel.