Thyrotoxicosis may present in many ways;severe vomiting as a prominent symptom of thyrotoxicosis is uncommon.In this paper,we report a 24-year-old Chinese male with hyperthyroidism who presented with recurrent severe vomiting.The patient had had intermittent vomiting for seven years and had lost approximately 15 kg of weight.Gastroscopic examinations revealed chronic gastritis and one occasion peptic ulcer.He was treated with antacid and proton pump inhibitors,but his symptoms had no relief.His presenting symptoms suggested hyperthyroidism and were confirmed by laboratory data.After a month of propylthiouracil therapy,his symptoms were relieved.It should be noted that hyperthyroidism patients can have unexplained vomiting,and that hyperthyroidism may coexist with peptic ulcer in rare cases.Awareness of such atypical presentations of hyperthyroidism may help to make a correct diagnosis. Thyrotoxicosis may present in many ways; severe vomiting as a prominent symptom of thyrotoxicosis is uncommon. In this paper, we report a 24-year-old Chinese male with hyperthyroidism who presented with recurrent severe vomiting. The patient had had intermittent vomiting for seven years and had lost approximately 15 kg of weight. Gastroscopy examinations revealed chronic gastritis and one occasion peptic ulcer. He was treated with antacid and proton pump inhibitors, but his symptoms had no relief. His presenting symptoms suggested hyperthyroidism and were confirmed by laboratory data. After a month of propylthiouracil therapy, his symptoms were relieved. It should be noted that hyperthyroidism patients can have unexplained vomiting, and that hyperthyroidism may coexist with peptic ulcer in rare cases. Awareness of such atypical presentations of hyperthyroidism may help to make a correct diagnosis.