BACKGROUND: The Achilles' heel of infrainguinal bypass grafts (IIBGs) is restenosis. Duplex ultrasound (DUS) surveillance is commonly undertaken to identify restenosis allowing intervention for graft salvage. We report the impact of DUS surveillance on patient outcomes alongside healthcare-associated costs. METHODS: Consecutive patients undergoing IIBG at our institution were included (January 2017-December 2020). Data on DUS surveillance (1-, 6-, and 12-month scans) were collated. Primary outcome was lower limb salvage rates at 2 years. Graft failure was defined by radiological evidence of significant graft stenosis ("at risk") or occlusion (with or without symptoms). Institutional costs for treatment associated with at-risk grafts were quantified. Follow-up was 100% complete at 2 years. RESULTS: Briefly, 254 patients had IIBG (196 men, median age 70 years). Of those, 192 patients (76%) entered DUS surveillance, and 109 (43%) completed it. In patients who completed surveillance (versus incomplete versus none) major lower limb amputation rates were 6.4% (vs. 12% and vs. 30%, P = 0.174 and P <
0.001, respectively). Enrolling in DUS surveillance was associated with improved limb salvage and survival rates compared to having no surveillance at all (Log rank P <
0.001). Managing graft failure led to 372 additional cross-sectional imaging studies, 302 outpatient reviews, 1,538 hospital admission days and 226 open and endovascular reinterventions, with a total additional National Health Service cost of £ 1,436,085/€1,683,912. Enrollment into a surveillance program was associated with higher costs. CONCLUSION: Enrolling in DUS surveillance following IIBG is associated with improved outcomes. Graft failure and its subsequent management confer additional costs. DUS surveillance is costly, but may be justified by improved limb-salvage rates and the associated reduction in amputation-associated costs.