Yellow fever is a hemorrhagic fever caused by a virus that is prevalent in Africa and South America. The virus that causes the disease is an arbovirus, which is spread by mosquitoes. Therefore, the habitat of mosquitoes that can spread this virus coincides with the major yellow fever outbreak area. It was called yellow fever because some of the patients with the disease had symptoms of turning yellow due to jaundice. Symptoms can be divided into incubation period, acute phase, and toxic phase. After the incubation period of 3-6 days, an acute phase appears. In the acute phase, symptoms such as fever, muscle pain, chills, headaches, loss of appetite, nausea, and vomiting appear. It is common for symptoms to disappear three to four days after these acute symptoms occur, but about 15% of patients will enter a toxic phase afterward. Patients with toxic phase develop fever again and rapidly develop symptoms such as jaundice, abdominal pain, and vomiting. In addition, bleeding can occur in the mouth, nose, eyes, and gastrointestinal tract because liver function is deteriorated and blood clotting factors are not properly produced in the liver. Acute renal failure may occur, and about half of patients entering a toxic phase die within 14 days.