Dysphagia is a common symptom in neuromuscular junction disorders, but it rarely occurs in isolation or is the presenting feature. We describe a patient presenting with isolated dysphagia to liquids. Electrophysiological studies, such as repetitive nerve stimulation and single-fiber electromyography, were normal. Serum anti-P/Q-type voltage-gated calcium-channel (anti-P/Q-type VGCC) and anti-acetylcholine receptor (AChR ab) antibodies were above the normal range. A computed tomography scan showed a mediastinal mass corresponding to a thymic carcinoma. After chemotherapy, surgical removal of the thymic carcinoma and radiotherapy, the patient no longer complained of dysphagia, AChR ab titers were reduced and anti-P/Q-type VGCC antibodies became negative. To the best of our knowledge, no previous reports of a paraneoplastic myasthenic syndrome related to thymic carcinoma with both anti-P/Q-type VGCC and AChR antibodies have been described.