Different etiologies of pleural effusion are diagnosed based on serum and plural fluid characteristics. Recently it has been found that the ProCalcitonin (PCT) might have the diagnostic value in exudative pleural effusion (PE). The aim of this study was to assess PCT level in plural fluid and serum to find the specificity and sensitivity of PCT for different etiologies of PE. This study was conducted on 80 patients with exudative PE (Parapneumonic; PE (20 cases), Tuberculosis; TB (20 cases), Malignant effusions (20 cases) and transudate PE (20 cases) to measure the serum and PE level of PCT. The mean Plural PCT was significantly higher in pleural PE of parapneumonic effusion (115.10 ±14.06 μg/mL). The cutoff point of value to explore PCT for diagnosing considered at 0.3 ng/mL and this cut-off calculated by using ROC method. It appears that only in parapneumonic pleurisity, a statistically significant area under curve was observed (P=0.001). The area under curve amount in blood PCT level for parapneumonic pleurisity versus non parapneumonic pleurisity was 0.44 with 95% confidence interval of 0.24-0.61 and specificity and sensitivity values for pleural fluid PCT were 0.42 and 0.42 (P=0.09). Present study showed that plural PCT level in parapneumonic pleurisy could have diagnostic value neither in TB nor in malignancies pleurisity patients. The pleural PCT has higher diagnostic accuracy comparing withserum PCT in differentiating parapneumonic pleurisy from non parapneumonic pleurisy. Both pleural fluid PCT and serum PCT were useful for assessing the severity of pneumonia with parapneumonic plural effusions.