Parapneumonic effusions develop as a complication of bacterial pneumonia and these children often require hospitalization. Most deaths are not caused by effusions themselves but are the result of acute pneumonia or sepsis. The mortality rate is low, and the incidence is highest in neonates. The main cause of parapneumonic effusion in children is S. pneumoniae, followed by Staphylococcus aureus, MRSA, other streptococci and staphylococci. The causative agents change with the advent of vaccines and antibiotic resistance. Symptoms may manifest immediately or after unsuccessful treatment of pneumonia. The patient may have usual symptoms of pneumonia. Children also complain of pleuritic pain, shortness of breath and they prefer laying down on the affected side. Laboratory diagnosis depends on the clinical picture, age, severity of the disease and complications. Ultrasound remains the best choice for diagnosing the presence of parapneumonic effusion. The results are visible immediately, and the patients are not exposed to radiation. The development of parapneumonic effusion occurs in three clinically significant phases, which represent a continuous spectrum. One phase can progress to another within a few hours or days. Exudative effusion is the first stage and is treated with antibiotic therapy. Untreated exudative effusions develop into fibrinopurulent effusions, and then in addition to antibiotic therapy, thoracic drainage with fibrinolytic therapy is required. The best fibrinolytic agent is alteplase. The third stage is organizational, which always requires surgical treatment, most commonly VATS.