Post-acute COVID-19 syndrome or COVID Long Haul Syndrome, was recently described as a syndrome characterized by persistent symptoms and delayed or long-term complications beyond 4 weeks from the onset of symptoms. The COVID-19 infection may trigger the immune system to overreact continuously even though the infection has resolved. Some patients with Post-acute COVID-19 syndrome generate auto-antibodies which attack their own healthy tissues. Some medical experts believed that the infection of COVID-19 can cause disfunction of the autonomic nervous system. The formation of tiny blood clots could also contribute to Post COVID-19 syndrome. Many patients have elevated levels of coagulation factors in the blood, which make them more susceptible to blood clotting. Many organs such as the heart, brain, lungs, legs, liver and kidneys have been shown to be damaged by tiny blood vessel clots. In addition, many patients may require symptomatic treatment to improve their quality of life. Post COVID-19 patients are recommended to have adequate hydration, plenty of rest, eat and sleep well and learn to manage stress effectively. In this review, we discuss the current status of research in Post-acute COVID-19 Syndrome. (Am J Transl Med 2021. 5 (3) :125-137).