Pleural diseases represent a number of pathologies that involve the pleura, pleural space and pleural liquid. These diseases are common and it is estimated that they affect around 3000 in a million persons yearly. Considering the number of conditions that can cause symptoms involving the pleura and pleural space, it’s important to have a systemic approach in diagnosis. Pleura is a serous lung membrane, made up of two layers, visceral and parietal pleura. Between them is the pleural space which normally contains around 0,26 mL/kg of pleural liquid. Most common pathology of the pleura are pleural effusions, which happens due to an imbalance in formation and reabsorption of pleural liquid. Common causes include pneumonia, congestive heart failure and malignancy. They can be divided in transudates and exudates based on the Light’s criteria. The diagnosis is made with chest radiography and ultrasound, but the most important part is the analysis of the pleural liquid obtained by thoracocentesis. In case the etiology in unclear, invasive diagnostic methods are available, such as pleural biopsy. Treatment is focused on the underlying cause. The second most common pathology is pneumothorax, which can occur spontaneously or be caused by trauma or iatrogenically. Diagnosis is set with an x-ray image or with ultrasound. Treatment is planed based on the clinical presentation and it involves oxygen therapy, needle aspiration and chest drain insertion. Most common malignant diseases of the pleura are metastases, especially those from lung and breast cancers. Malignant pleural mesothelioma is the most important primary pleural tumour and is associated with long-term asbestos exposure. There are three histological variants of the mesothelioma: epithelioid, sarcomatoid and biphasic. It’s necessary to confirm the diagnosis histologically from the tissue sample obtained by biopsy, while CT is used for staging. Mesothelioma is an incurable disease so the focus is on palliative care. Treatment includes chemotherapy, immunotherapy, radiotherapy and surgical interventions.