Abstract: Objective  To study the clinical value of thoracoscopy and protein fingerprinting technique（PFT）in improving the early diagnosis of cancer and tuberculous pleural effusions.  Methods  Of 121 cases with pleural effusions confirmed by imaging examination, thoracoscopy, pathological or bacteriological examination, 30 cases with malignant pleural effusion and 50 cases with tuberculous pleural effusion were detected simultaneously pleural fluid protein fingerprint peaks, and the data were statistically analyzed.  Results  There were 7 different protein peaks between two groups（m/z 5335, 8048, 11 700, 11 670, 15 982, 11 683 and 7700）. The protein peaks m/z 11 670 and m/z 11 700 were selected to establish the diagnosis model of malignant effusion, which was statistically significant between two groups (χ²=26.55, P<0.01). Its sensitivity and specificity for the malignant effusion were 83.3%（25/30）and 76.0%（38/50）, respectively. The protein peaks m/z 5335 and m/z 8048 were used to establish the diagnosis model of tuberculous pleural effusion, which was significantly different between two groups (χ²=9.86, P<0.01). The sensitivity and specificity for the tuberculous effusion were 52.0%（26/50）and 83.3%（25/30）, respectively.  Conclusion  The pleural fluid protein fingerprint technique is a simple, fast and effective means for the differential diagnosis of tuberculous and malignant effusions, but need be further studied in the interpretation of protein maps.

Key words: Pleural effusion, Thoracoscopy, Peptide mapping, Diagnosis,differential