Although acute COVID-19 usually lasts for 12 weeks from the onset of symptoms, some patients experience variable persistent symptoms. Post-COVID-19 syndrome is defined as persistent symptoms and/or long-term complications that appear during or after COVID-19, persist for more than 12 weeks, and cannot be explained by an alternative diagnosis. The common symptoms of post-COVID-19 syndrome include general, pulmonary, hematological, cardiovascular, neuropsychiatric, renal, endocrine, gastroenterological, and dermatological symptoms. As the natural course and pathophysiology of COVID-19 are not yet clear, close monitoring is needed for various sequelae in multiple organs that occur in post-COVID-19 syndrome. In particular, patients who have been hospitalized in the intensive care unit or who have recovered from severe COVID-19 require close monitoring for the development of post-COVID-19 syndrome. Multidisciplinary collaboration is essential to provide integrated outpatient care for patients with post-COVID-19 syndrome.