Background: Ventilator-associated pneumonia (VAP) is a prevalent infection in intensive care units (ICUs) that occurs after more than 48 hours of mechanical ventilation. Procalcitonin is a precursor of the hormone calcitonin, produced by the C-cells of the thyroid gland. Its levels in serum can rise significantly in response to bacterial infections, making it a useful marker for diagnosing and assessing the severity of pneumonia. This study focuses on the correlation between serum procalcitonin levels and the severity of VAP, aiming to provide valuable insights for patient management. Methods: A cross-sectional study at Dr. Wahidin Sudirohusodo hospital, Makassar, Indonesia. The population of this study were patients aged > 18 years admitted to the intensive care unit in May 2024 until the sample size was fulfilled. Diagnosis of VAP using thoracic x-rays with the discovery of new infiltrates after 48 hours of mechanical ventilator installation then measuring blood procalcitonin. Results: This study involved 78 subjects. Male gender was 48 (61.5%) subjects, female was 30 (38.5%) subjects. The mean age of the study subjects was 55.9 +14.45 years. Elevated procalcitonin values were found in 72 (92.3%) subjects. PSI score was low risk in 47 (60.3%), moderate risk in 28 (35.9%) and high risk in 3 (3.8%) subjects. A significant positive correlation was found between serum procalcitonin levels and PSI scores (r=0.428, p<0.001), indicating that higher procalcitonin levels are associated with increased VAP severity. Conclusions: In this study, it can be concluded that the severity of VAP as measured by the PSI score is positively correlated with high procalcitonin values