About one third of the world's population is infected with tuberculosis (TB) and each year, about 1.5 to 2 million people die from TB. Procalcitonin (PCT) is an inflammatory marker that its level has variable results. There are some discussions in the utilization of PCT as a diagnostic marker in active pulmonary TB. The aim of this study was to compare serum PCT before and after treatment in patients with pulmonary TB. Materials and Methods: This study was conducted on patients with pulmonary

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... . Data were collected using a check list. The serum level of PCT was measured by ELISA test at the beginning and after six months of treatment. All data were analyzed using SPSS 16. Results: Forty-two patients with active pulmonary TB entered in this study. The mean age of the patients was 45.48±12.54 years and 54.8% of them were male. Most of the patients (59.5 %) were rural inhabitants. There was a family history of TB in 26% of patients. The most common symptom (45.2%) was cough. Mean PCT prior to treatment was 1.25±0.98 ng/ml. and 81% of the patients had PCT higher than 0.5 to 5. After treatment PCT level reduced significantly (P<0.001). The mean erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) before treatment were 45.88±21.87 and 7.16±3.98 respectively that were reduced significantly after treatment (P<0.001). Neutrophil counts before treatment was 6221±3161 Cells per ml. and decreased statistically significant after treatment (P=0.01). Conclusion: Our results showed that the PCT levels in pulmonary TB were high in active disease and reduced after treatment. PCT level may be used for follow-up as a discriminative marker between active and cured pulmonary TB and predict treatment response, although the PCT assay cannot be substituted for microbiological and pathological data.