Two infants with five separate episodes of extravasation from hyperalimentation catheters are described. Three were intrathoracic and two were retroperitoneal, one of the latter producing clinical ascites. Clinical respiratory distress or ascites developing in an infant undergoing hyperalimentation may indicate vein wall perforation with extravasation into the pleural or abdominal cavities or the retroperitoneum. Questionable situations may be readily resolved by contrast injection through the catheter. Suboptimal position of the catheter tip and venous thrombosis seem to be major contributors to this problem. Prompt recognition and removal of the catheter are generally sufficient to correct the situation.