To determine the safety and efficacy of chronic percutaneous pericardial drainage in children, pigtail catheters were inserted over curved guidewires under fluoroscopic control into the pericardial space in 7 consecutive children with pericardial effusion. Pericardiocentesis was therapeutic (for tamponade) in 1 child, diagnostic in 4 and both therapeutic and diagnostic in 2. The children were 0.5 to 16 years old and weighed 5 to 65 kg. Underlying diagnoses included cancer (3 children), congenital heart disease (2 children) and immunodeficiency and hemolytic uremic syndrome (1 each). When unmodified pigtail catheters, designed for angiography, were used (as in the first 3 children), either the catheters clotted within 36 hours, necessitating operative pericardial drainage, or repeated heparin infusions were required to keep the catheter patent. However, when 8Fr catheters were modified by placing 0.050-inch side holes along the distal shaft, the catheters remained patent and effectively drained the pericardial space for 3 to 7 days. Heparin infusion was not required, no child managed with the modified catheters required subsequent drainage and no complications occurred. In conclusion, percutaneous pericardial drainage is safe, even in small children, and can be effective chronically if catheters with large drainage holes are used.