Investigations of the heart rate variability (HRV) in an 11-year-old boy with multisystemic inflammation syndrome in children (MIS-C) and a 16-year-old girl with postural orthostatic tachycardia syndrome (POTS) after SARS-CoV鈥? infections are presented. Results: The MIS鈥慍 is characterized by a maximum suppression of the HRV during ECG monitoring on the pediatric intensive care unit. After intravenous administration of immunoglobulins HRV supppression is rapidly reversible. The POTS is characterized by a heart rate increase of more than 40鈥痓pm and the complete collapse of the HRV in the active standing test that can probably explain some chronic problems after SARS-CoV鈥? infections. In the MIS鈥慍 patient we found autoantibodies against receptors of the autonomic nervous system. Summary: The examination of HRV in patients with COVID-19 are initial descriptions,which can enrich our knowledge of the pathophysiology of this new disease.