OBJECTIVES--To review efficacy and safety of endovascular stent implants in children < 1 year of age with congenital heart lesions. DESIGN--Retrospective study of patients in a tertiary care setting. PATIENTS--26 children (median age of 4.7 months, range 2 days to 1 year) with various vascular obstructive lesions. INTERVENTION--Percutaneous or intraoperative implantation of balloon expandable endovascular stents. RESULTS--Optimal stent placement was obtained in 31 of the 37 deployed implants. Complications resulted primarily from stent malpositioning and one episode of bleeding at a puncture site. Stent implantation in three patients with a restrictive arterial duct allowed for patency and five patients with conduit stenosis had mean (SD) right ventricule to systemic artery pressure ratios falling from 0.99 (0.20) to 0.52 (0.18) (P < 0.05). In 10 patients with pulmonary artery stenosis, the mean vessel diameter increased from 2.8 (0.9) mm to 5.8 (1.4) mm (P << 0.001). No clinical improvement was seen in two patients because of diffuse hypoplasia of the pulmonary vessels. Nine of 10 patients with miscellaneous obstructive lesions improved clinically. Recatheterisation was performed in 19 patients (median 8 months, range 12 days to 28 months) and 11 patients required redilatation (17 stents). CONCLUSIONS--Stent implantation is technically feasible in infants and under specific circumstances may provide an alternative to surgical palliation or avoid reoperation. The long term impact on clinical course, however, involves further interventions directed at stent management.