Malignant pleural effusion (MPE) refers to the presence of neoplastic cells in the pleural fluid. Approximately 40 000 people per year in the UK are affected by MPE and it is associated with significant morbidity and an overall poor prognosis. Management should be prompt and care plans should be individualized and involve a multidisciplinary team of healthcare professionals. This article reviews the pathophysiology of MPE along with available investigations and management strategies for these patients.