We reported two patients with polymyositis (PM) associated with primary biliary cirrhosis (PBC) who noticed head-drop as the incipient symptom. Muscle computed tomography showed marked hypodensity in the paravertebral muscles as compared with limb muscles. Patient 1, a 48-year-old female, was admitted in our hospital for the examination because of her neck and proximal limb muscle weakness, increasing fatigability, and abnormal serum liver and muscle enzyme levels. She felt her throat was so dry at age 39, and she noticed weight loss at age 41 and head-drop at age 42. A diagnosis of PM was made from symmetrical proximal limb muscle weakness, elevated creatine kinase (CK) level, and the electromyographic and muscle biopsy findings. Her illness was also diagnosed as PBC because of the increased serum alkaline phosphatase and IgM immunoglobulin levels, and liver biopsy findings. The anticentromere antibody titer was positive, though the antimitochondrial antibody titer negative. The HLA typing was DR 4, DR 8, DR53, DQ 4, DQ 6, DRB 1 (0405/0803). She was placed on 60 mg of prednisolone/day for PM and 300 mg of ursodeoxycholic acid/day for PBC. Patient 2, a 49-year-old female, presented with proximal limb muscle weakness and head-drop. Serum CK, alkaline phosphatase and IgM immunoglobulin levels were increased. The antimitochondrial antibody titer was positive. She began to have 60 mg of prednisolone/day, and 50 mg of azatioprine/day and 300 mg of ursodeoxycholic acid/day were subsequently added. PM associated with PBC seems to be rare, because only 21 cases have been described in literature. In those patients, marked paravertebral muscle atrophy has never been described. Further study is necessary to examine whether or not the preferential paravertebral muscle involvement is a striking and diagnostic finding for PM with PBC.