Background: Community acquired pneumonia is a common and deadly condition, which remains a major cause of morbidity and mortality throughout the world. Chlamydia psittaci pneumonia is responsible for less than 5% of community-acquired pneumonia with a fatality rate of 1%. Nonetheless, it is underestimated due to low awareness of the disease and atypical clinical presentation in a majority of the cases. Metagenomic next-generation sequenc-ing can help us diagnose and clarify the etiology in time. Methods: We reported a case of an 85-year-old man who presented with intermittent fever and cough with wheez-ing for 4 days and did a review of related literature. Results: The patient was admitted to our department due to severe CAP and multiple organ dysfunction. After ad-mission, we applied an empirical antibiotic strategy, performed intubation and invasive ventilation, fluid resusci-tation, vasoactive drugs and supportive care. On the third day of admission, metagenomic next-generation se-quencing results of blood and bronchoalveolar lavage fluid suggested Chlamydia psittaci. We made a diagnosis of sever Chlamydia psittaci pneumonia and adjusted antibiotics to minocycline combined with azithromycin two days after admission. The patient was successfully cured with a good prognosis. Conclusions: Detecting the pathogen as early as possible and achieving accurate diagnosis are essential in infected patients. We can benefit from careful application of metagenomic next-generation sequencing. Clin. Lab. 2022;68:xx-xx. DOI: 10.7754/Clin.Lab.2021.211127)