Background: A closed pleural biopsy is commonly performed for diagnosing patients exhibiting pleural effusion if prior thoracentesis is not diagnostic. However, the diagnostic yield of such biopsies is unsatisfactory. Instead, a thoracoscopic pleural biopsy is more useful and less painful. Methods: We compared the diagnostic yield of needle thoracoscopic pleural biopsy performed under local anesthesia with that of closed pleural biopsy. Sixty-seven patients with pleural effusion were randomized into groups A and B. Group A patients were subjected to closed pleural biopsies, and group B patients were subjected to pleural biopsies performed using needle thoracoscopy under local anesthesia. Results: The diagnostic yields and complication rates of the two groups were compared. The diagnostic yield was 55.6% in group A and 93.5% in group B (p<0.05). Procedure-related complications developed in seven group A patients but not in any group B patients. Of the seven complications, five were pneumothorax and two were vasovagal syncope. Conclusion: Needle thoracoscopic pleural biopsy under local anesthesia is a simple and safe procedure that has a high diagnostic yield. This procedure is recommended as a useful diagnostic modality if prior thoracentesis is non-diagnostic.