Introduction & Objective: As the accumulation of fluid in the pleural cavity is a common finding in patients with cancer, its diagnosis deserves careful consideration., The aim of this study was compare two methods of thoracoscopy and acupuncture needle biopsy in the diagnosis of malignant pleural effusion in patients. Materials & Methods: In a cross-sectional study, 50 patients with pleural effusion, suspected to have malignant pleural effusion, who referred to Shahid Beheshti Hospital (Qom) during the 3 years (2011 to 2014), were selected through available sampling Was performed. Results: A total of 50 patients with pleural pleural effusion, suspected to have malignant pleural effusion, were included in the study, which included 21 males and 29 females with 14 patients in the age group less than 50 years old and 36 subjects in the age group > 50 years. Thoracoscopic medication had a sensitivity of 86%, 100%, positive predictive value of 100%, and a negative predictive value of 77%. The susceptibility of 53%, 100%, 100% positive predictive value and negative predictive value of 66% and diagnostic accuracy were obtained from the needle closure biopsy method. Conclusions: Considering the high sensitivity of the thoracoscopic medical technique to the pleural biopsy, the similar complications in both methods, and the possibility of taking actions during thoracoscopic medication, thoracoscopy seems to be the first and the best after thoracentesis negative in patients Suspected of malignant pleural effusion. Although the cost of doing this is higher, due to the health plan, there is little cost to the patients and, on the other hand, with timely diagnosis, reduces the costs of readmission and the resulting problems.