Objective: The novel coronavirus SARS-CoV-2 (COVID-19) rapidly escalated from its origin in an animal market in Wuhan, China in December 2019 to a global pandemic, and the lungs are the most frequently affected organ. The aim of this study was to investigate the relationship between pulmonary function test parameters and laboratory parameters in COVID-19. Method: A total of 60 patients who were admitted to the chest diseases department and intensive care unit of our hospital and were diagnosed with COVID-19 by real-time PCR analysis of nasopharyngeal swabs were evaluated. Pulmonary function tests and laboratory parameters at admission and on day 7 of treatment were analyzed. Results: On day 7 of treatment, white blood cell count, CRP, and fibrinogen level were significantly lower than at admission (p=0.002, 0.001, and 0.001, respectively), while forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) values were significantly higher compared to admitting values (p=0.001 for both). Correlation analysis of the changes in respiratory function values and laboratory parameters during follow-up (day 1 to day 7 of treatment) revealed that CRP level was positively correlated with FEV1 (r=0.616, p=0.01) and FVC values (r=0.51, p=0.01). Fibrinogen level was also positively correlated with FEV1 (r=0.345, p=0.01) and FVC (r=0.357, p=0.01). Conclusion: Fibrinogen and CRP levels are easily accessible parameters that may help identify improvement or deterioration in pulmonary function in COVID-19 patients during follow-up and discharge while reducing the risk of transmission.