Patients with malignant pleural effusions (MPEs) are heterogenous in their disease course, symptom severity, responses to cancer therapies, fluid recurrence rates, and thus need for definitive fluid control measures. To tailor the most appropriate treatment for individual patients, clinicians need to 'phenotype' the patients and predict their clinical course. This review highlights the recent efforts to develop better predictive tools and knowledge gaps for further research.The LENT scoring system, which includes pleural fluid lactate dehydrogenase, performance status, serum neutrophil-to-lymphocyte ratio and tumor type, allows prediction of the survival of patients with MPE. Symptomatic response after therapeutic pleural drainage is highly variable; ongoing studies aim to identify those who would derive symptomatic benefit from fluid drainages. Multivariate analysis found that patients with low pleural fluid pH [odds ratio (OR) 37.04], large effusions (OR 3.31), and increasing age (OR 1.02) were more likely to require pleurodesis or indwelling pleural catheter placement for fluid control. Better predictive tools for rate of fluid recurrence and likelihood of successful pleurodesis would help guide clinical decision-making.Phenotyping MPE would guide the formulation of optimal management for individual MPE patients.