Retrograde arterial catheterization was performed in 105 infants and small children (median age 6 mo) using a 3.2 French pigtail catheter made of ultrathin walled white Teflon. Three catheter lengths were used, (40, 50, and 65 cm). Pressure recordings and ease of sampling were judged excellent in all. All 118 angiograms (60 ventricular) were performed without complication except for two episodes of external catheter rupture. Angiographic quality was rated excellent in 41%, good in 39%, fair in 18%, and poor in only 2%. Among the 81 patients in whom only this catheter was used percutaneously, pedal pulses were lost in 5%. Postcatheterization testing identified ranges of volume and flow-rate characteristics which included 8 ml at 15 ml/sec (40 cm length), at 11 ml/sec (50 cm length), and at 9 ml/sec (65 cm catheter). We conclude that this small catheter is relatively safe and satisfactory for retrograde catheterization of infants and small children.