An 8-week-old preterm boy experienced respiratory deterioration due to unilateral pleural effusion. Intra-abdominal extravasation of parenteral fluid with leakage into the pleural cavity was suspected based on biochemical analysis of the effluent. Perforation of the central venous catheter in the peritoneal cavity was subsequently confirmed by contrast roentgenography. As in peritoneal dialysis and hepatic hydrothorax, pleuroperitoneal communication needs to be considered in patients exhibiting pleural effusion with a central venous line below the diaphragm.