A 54-year-old woman developed drop head syndrome (DHS), Raynaud\'s phenomenon and creatine kinase (CK) elevation. She did not meet the international classification criteria of dermatomyositis/polymyositis, as we observed no muscle weakness, grasping pain or electromyography abnormality in her limbs, and anti-aminoacyl tRNA synthetase (ARS) antibody was negative. Cervical magnetic resonance imaging and a muscle biopsy of the trapezius muscle revealed myositis findings as the only clinical observations in muscle. These findings, along with her anti-U1-ribonucleoprotein (RNP) antibody positivity and leukopenia, resulted in a diagnosis of mixed connective tissue disease (MCTD). Prednisolone treatment significantly improved her myositis. To our knowledge, this is the first report of DHS as the only muscle complication of MCTD.