Background: Pleural effusion refers to the excessive or abnormal accumulation of fluid in the pleural space. Pleural effusion often present as a common diagnostic dilemma to the physicians in clinical practice (1) as the differential diagnosis is wide and may indicate the presence of pleural, pulmonary, or extra pulmonary disease, as the no cause can be found in many cases in spite of care full evaluation Methods: This study was carried out on 65 patients with pleural effusion admitted to the pulmonary medicine ward between August 2008 to August 2011. Etiological diagnosis of pleural effusion was confirmed according to appropriate clinical and /or laboratory findings or criteria. Results: Sixty five patients with pleural effusion of different etiology were studied. The commonest type of effusion being tuberculosis 34(52.3%) followed by malignancy 17(26.15%), transudation effusion 7(10.7%) parapnemonic effusion 5(7.6%) and 2(3.07%) cases of empyema. Conclusion: The findings of the present study in confirmation with previous studies indicate that tuberculosis and malignancy are the most probable cases of exudative pleural effusion. Additionally, those results confirm that, despite the development of new diagnostic procedures, pleural fluid analysis and pleural biopsy remain the best diagnostic methods for evaluation of pleural effusion, as well as for determining the etiology in patients with pleural effusion.