During a 32-month period, 79 extremities in 76 children (age 1 day-13 years, mean = 31 months) were evaluated with regard to iatrogenic vascular injuries. Prospectively, 42 children were studied pre- and post-cardiac catheterization. Ten of these children sustained vascular injuries (incidence = 24%). Thirty-four additional children were referred because of 35 iatrogenic vascular injuries as a result of transfemoral cardiac catheterization (n = 20), umbilical artery catheterization (n = 10), or recent surgery (n = 5). All 45 injuries were evaluated by lower extremity segmental Doppler pressure measurements in addition to routine physical examination at the time of injury and at frequent follow-up. An ankle/brachial pressure index (ABI) less than 0.9 was considered abnormal. Selected children (ABI less than 0.9 for greater than 30 days) underwent orthoroentgenograms to assess limb growth. The average ABI immediately following injury was 0.34 +/- 0.33. Thirty-four injuries were treated nonoperatively. Twelve injuries were excluded from further study due to death (n = 7) or being lost to follow-yp (n = 5). A return of ABI to normal was seen from 1 day to 2 years in 93% of children treated with heparin (n = 14) compared to 63% of children who were simply observed (n = 8) (p less than 0.10). The initial severity of ischemia did not correlate with the subsequent rate of improvement. Only patients with absent femoral pulses were selected for operative intervention, which consisted of aortic thrombectomy (n = 2), femorofemoral bypass (n = 2), femoral artery patch angioplasty (n = 1), or femoral artery thrombectomy (n = 7) with no mortality. Nine patients had immediate return of a normal ABI after surgery. A delayed return of ABI to normal occurred in the other two. Nine per cent of surgically treated children and 23% of nonsurgically treated children developed leg length discrepancies (0.5-3.0 cm) as a result of ischemia lasting greater than 30 days. Overall, 91% of the children in this series eventually regained normal circulation following injury and no child lost a limb. This study indicates that iatrogenic pediatric vascular injuries are common and can result in significant limb growth impairment. Immediate operative intervention is highly successful when the injury is proximal to the common femoral artery bifurcation and avoids the prolonged ischemia seen with nonoperative therapy. For more distal occlusions, heparin therapy provides better results than simple observation. Although therapeutic intervention for these injuries is generally successful, a limb length discrepancy rate of 14% mandates that indications for invasive vascular monitoring and diagnostic procedures be strict.