While the scientific evidence in favour of negative pressure wound therapy (NPWT) dressings on sutured incisions in the prevention of surgical site infections (SSIs) has increased, the cost-effectiveness after vascular surgery has not been evaluated. The aim of this study was to evaluate the cost-effectiveness of NPWT compared to standard dressings for the prevention of SSIs after open inguinal vascular surgery. Patient data were retrieved from the randomised INVIPS-trial's open arm, which included patients randomised to either NPWT or standard dressings. The patients were surveyed for SSIs for 90 days postoperatively. The patients' individual cost data were included and analysed from a healthcare perspective. The patients' quality of life was measured using the Vascuqol-6 questionnaire pre- and 30 days postoperatively. Cost-effectiveness of NPWT was determined by decreased or equal total costs and a significant reduction in SSI incidence. The mean vascular procedure-related costs at 90 days were €16,621 for patients treated with NPWT (n = 59) and €16,285 for patients treated with standard dressings (n = 60), p = 0.85. The SSI incidence in patients treated with NPWT was 11.9% (n = 7/59) compared to 30.0% (n = 18/60) with standard dressings, p = 0.015. This corresponds to an increased mean cost of €1,853 per SSI avoided. The cost-effectiveness plane of incremental vascular procedure-related costs and difference in Vascuqol-6 score showed that 42% of estimates were in the quadrant where NPWT was dominant. NPWT is considered cost-effective over standard dressings in patients undergoing open inguinal vascular surgery due to reduced SSI incidence at no higher costs. Copyright © 2020 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.