Muscle affection related to systemic sclerosis (Myo-SSc) and systemic erthrymatoues (Myo-SLE) is a disabling and unpredictable complication of SSc and SLE so the assessment of muscle according to the European Neuromuscular Centre (ENMC) criteria. The clinical, serological, laboratory as (serum aldolase, creatine kinase (CK), alanine transaminase (ALT), aspartate transaminase (AST) and C-reactive protein (CRP) and muscle biopsy features were compared between patients with and without histological evidence of myositis.