BACKGROUND Since December 2019, novel coronavirus (COVID-19) infection has been identified as the cause of an outbreak of respiratory illness in Wuhan, China. The classic presentation of COVID-19 infection was described as fever, myalgia, cough, and fatigue. Whether coronavirus can directly attack the endocrine glands is unclear. OBJECTIVE Post-viral subacute thyroiditis (SAT, de Quervain thyroiditis) has been reported following other viral infection. A limited number of SAT after COVID-19 infection have been reported up to now. METHODS Here, we reported 6 patients with SAT and positive COVID-19 serology tests. Demographic, clinical, biochemical, and imaging data were presented. RESULTS In this study, 6 patients (4 women and 2 men) with clinician manifestations and physical examination in favor of SAT were described. Cervical ultrasonography showed bilateral hypoechoic areas in the thyroid gland which was suggestive of SAT. Elevated C-reactive protein, erythrocyte sedimentation rate, free thyroxine, free tri-iodothyronine, and undetectable thyrotropin were found in laboratory evaluations. Both IgM and IgG were positive for COVID-19 infection, but the PCR tests were negative in all patients. Patients had history of working in a COVID center and/or family member hospitalized due to COVID-19 pneumonia. Patients were followed up for 1 month and were treated effectively with steroids. CONCLUSIONS This report may help physicians to identify lesser-known manifestations and complications of COVID-19. Early diagnosis of COVID-19 infection results in the prevention of further transmission.