Purpose Especially in elderly and multimorbid patients, Coronavirus Disease 2019 (COVID-19) may result in severe pneumonia and secondary complications. Recent studies showed pneumothorax in rare cases, but tension pneumothorax has only been reported once. Case presentation A 47-year-old male was admitted to the emergency department with fever, dry cough and sore throat for the last 14 days as well as acute stenocardia and shortage of breath. Sputum testing (polymerase chain reaction, PCR) confirmed SARS-CoV-2 infection. Initial computed tomography (CT) showed bipulmonary groundglass opacities and consolidations with peripheral distribution. Hospitalization with supportive therapy (azithromycin) as well as non-invasive oxygenation led to a stabilization of the patient. After 5 days, sputum testing was negative and IgA/IgG antibody titres were positive for SARS-CoV-2. The patient was discharged after 7 days. On the 11th day, the patient realized pronounced dyspnoea after coughing and presented to the emergency department again. CT showed a right-sided tension pneumothorax, which was relieved by a chest drain (Buelau) via mini open thoracotomy. Negative pressure therapy resulted in regression of the pneumothorax and the patient was discharged after 9 days of treatment. Conclusion Treating physicians should be aware that COVID-19 patients might develop severe secondary pulmonary complications such as acute tension pneumothorax.