All attempts at subclavian venous catheterization by the Pediatric Surgery Service done during a one and one-half year period at the Children's Hospital of Los Angeles were prospectively studied. Catheterization was attempted in 107 patients with a mean age of 9.8 years. Cannulation of the vein was successful 89 times (71 per cent) with the major complications being arterial puncture (8.0 per cent), pneumothorax (2.4 per cent) and abnormal position (12.8 per cent). Fluoroscopy was a valuable adjunct when used, resulting in an 86 per cent success rate. The serious complication rate was similar between left and right-sided attempts, but more catheters were abnormally positioned during right-sided attempts (15.7 versus 5.2 per cent). Percutaneous insertion of subclavian venous catheters can be accomplished in infants and children with low morbidity. Cannulation of the left subclavian vein can be accomplished with a similar success rate and a lower malposition rate than the right side. Fluoroscopy is a useful tool to assist in the correct placement of the catheter.