Background: This study aimed to compare the serum levels of procalcitonin in the patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and the patients with chronic obstructive pulmonary disease (COPD) in the emergency ward of Afzalipour Hospital in Kerman. background: This study aimed to compare the serum levels of procalcitonin in the patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and the patients with chronic obstructive pulmonary disease (COPD) in the emergency ward of Afzalipour Hospital in Kerman. Methods: This cross-sectional study was conducted on 45 patients with stable COPD and 45 patients with AECOPD. Patients were divided into four groups based on COPD severity assessment. Serum procalcitonin levels were measured using an ELISA kit. Results: The mean age of patients in the exacerbation and the stable group was 60.97±12.61 and 62.53±11.04 years, respectively. Serum procalcitonin levels in two exacerbation groups (215.22±19.84) were higher than stable groups (127.92±8.97) (P=0.001). The accuracy of this test for diagnosing acute attack in terms of AECOPD was 77%, and the serum procalcitonin level of 132.6 was found to be the best cut-off point to diagnose acute disease. The mean serum procalcitonin levels of stage D patients in the acute attack group were substantially higher than those of stages D and B patients in the stable group (P = 0.001). Serum procalcitonin levels were related to body mass index (P=0.01), post-bronchodilator FEV1/FVC (P=0.028), and the number of hospitalizations per year (P=0.001). By increasing the serum procalcitonin levels, BMI and number of admissions per year increase, and post-bronchodilator FEV1/FVC decreases. method: This cross-sectional study was conducted on 45 patients with stable COPD and 45 patients with AECOPD. Patients were divided into four groups based on COPD severity assessment. Serum procalcitonin levels were measured using an ELISA kit. Conclusion: The mean serum levels of procalcitonin in the group with attacks due to COPD was significantly higher than the stable group. result: The mean age of patients in the exacerbation and the stable group was 60.97±12.61 and 62.53±11.04 years, respectively. Serum procalcitonin levels in two exacerbation groups (215.22±19.84) were higher than stable groups (127.92±8.97) (P=0.001). The accuracy of this test for diagnosing acute attack in terms of AECOPD was 77%, and the serum procalcitonin level of 132.6 was found to be the best cut-off point to diagnose acute disease. The mean serum procalcitonin levels of stage D patients in the acute attack group were substantially higher than those of stages D and B patients in the stable group (P = 0.001).Serum procalcitonin levels were related to body mass index (P=0.01), post-bronchodilator FEV1/FVC (P=0.028), and the number of hospitalizations per year (P=0.001). By increasing the serum procalcitonin levels, BMI and number of admissions per year increase, and post-bronchodilator FEV1/FVC decreases. conclusion: The mean serum levels of procalcitonin in the group with attacks due to COPD was significantly higher than the stable group. other: -