Concurrent presentation of acute hepatitis A virus (HAV) infection and Graves’ disease has not been reported in literature worldwide. Although there is no well-established mechanism that explains the induction of Graves’ disease by HAV to date, our case suggests that HAV infection may be responsible for inducing Graves’ disease. A healthy 27-year-old female presented fever, palpitation, and diarrhea, and she was subsequently diagnosed as acute HAV infection. Concurrently, she showed hyperthyroidism, and the diagnosis was made as Graves’ disease. She had never had symptoms that suggested hyperthyroidism, and previous thyroid function test was normal. Acute HAV infection was recovered by conservative management, however, thyroid dysfunction was maintained even after normalization of liver enzymes. Methimazole was used to treat Graves’ disease. We report a case of concurrent acute HAV infection and Graves’ disease in a patient without preexisting thyroid disease. This suggests that HAV infection may be a trigger for an autoimmune thyroid disease in susceptible individuals. (Korean J Gastroenterol 2018;71:354-358)