Objectives: To evaluate the etiologies, clinical, paraclinical characteristics of patients with pleural effusions. Method: This is a cross-sectional descriptive study on 51 patients with pleural effusion, who were treated at the Central Hospital of Thai Nguyen. Results and conclusions: The average age was 57.9 +/- 16,5. The common symptom: hacking cough: 52.9 percent, sputum: 29.4 percent, chest pain: 25.4 percent, dyspnea: 66.7 percent, fever or night sweats: 52.9 percent, weight loss: 19.6 percent, pleural effusion syndrome: 88.2 percent of cases. Chest Xray: freedom of effusion moderate and more 58.8 percent, the little 41.2 percent. Parenchymal lesions, interstitial is 31.4 percent. Pleural ultrasound demonstrated free pleural effusion in 92.2 percent, loculated pleural effusion and pleural compartmentalization: 7.8 percent, pleural thickening: 27.5 percent. On chest CT Scanner, free pleural effusion is 80.9 percent, loculated pleural effusion and pleural compartmentalization: 19.1 percent, pleural thickening, parenchymal lesions, interstitial: 66.7 percent.