Abstract Background: We aimed to evaluate the clinical and laboratory characteristics and aetiological factors of patients who underwent pericardiocentesis for moderate to large pericardial effusion. Method: A total of 38 patients who underwent pericardiocentesis due to moderate-severe pericardial effusion and not related to cardiac surgery were included in the study. Results: The male-to-female ratio was 2.16, and found to be 7.5 in patients over 3 years of age. Mean age and body weight of the patients were 69.4 ± 74.9 months and 22.5 ± 22.4 kg. Dyspnoea (51.7%) was the most common complaint, followed by chest pain (37.9%). Tamponade was present in 23.7% of the patients. The largest diameter of effusion was 24.4 ± 10.4 mm. The amount of fluid drained was 279.24 ± 279 ml. Macroscopic appearance was serous in 12 (34.3%), and haemorrhagic in 18 (51.4%). No complication related to procedure was seen. Aetiology for efusion was infectious in 26%, idiopathic in 18%, iatrogenic in 11%, rheumatological in 11%, malignancy in 8%, cardiomyopathy in 8%, and other factors related in 18%. Of the 38 patients, 16 received nonsteroidal anti-inflammatory drugs (NSAID), and colchicine and corticostreoid were added in nine and two patients, respectively. A total of eight (21%) patients died during follow-up. Conclusion: In conclusion, percutaneous pericardiocentesis can be applied safely and the underlying aetiology is decisive in the prognosis of the patient. Although pericardial effusion in children is often due to inflammation of the pericardium, it can develop as a finding of many local or systemic diseases that should be kept in mind.