Background and purpose: Coronavirus disease 2019 (COVID-19) is a multi-organ illness characterized by significant involvement of the coagulation cascade, immune response, and inflammation. This investigation aimed to explore the significance of various biomarkers, such as interleukin 6 (IL-6), lactate dehydrogenase (LDH), D-dimer, and N-terminal prohormone of brain natriuretic peptide (NT-proBNP), concerning lung complications in COVID-19 patients. Materials and methods: This retrospective study was conducted at Imam-Sajjad Hospital in Ramsar, Mazandaran, from May to August 2021 and focused on all COVID-19 patients with lung involvement who were admitted. An experienced radiologist assessed each patient's computed tomography (CT) scans and assigned a lung involvement score ranging from zero to 10 for each lung. These scores were categorized as mild (0-10), moderate (10-15), or severe (15-20). In addition to demographic data, serum levels of IL-6, LDH, D-dimer, and NT-proBNP were obtained from patient records, and all the achieved data were statistically analyzed. Results: A total of 154 patients were included. The distribution across mild (27. 3%), moderate (33. 7%), and severe (39%) lung involvement in COVID-19 was observed. Notably, levels of IL-6 (P=0. 002), D-dimer (P=0. 035), and LDH (P<0. 001) exhibited variations among these three groups of COVID-19 lung involvement. Furthermore, statistically significant positive correlations were observed between the calculated lung involvement score and plasma levels of IL-6 (P=0. 008, r= 0. 280), D-dimer (P=0. 008, r= 0. 307), and LDH (P<0. 001, r= 0. 320). Conclusion: This study suggests that plasma levels of biomarkers, including IL-6, D-dimer, and LDH, may be associated with lung involvement in COVID-19 patients.