OBJECTIVE: Intravascular ultrasound (IVUS) can be used to optimize the deployment of stents. The aim of this study was to assess the acute and long-term medical costs of the use of IVUS through the results of the 'REStenosis after Intravascular ultrasound STenting' (RESIST) study. METHODS: One hundred and fifty-five patients were randomized to routine stent deployment with (n = 79) versus without (n = 76) IVUS guidance, with clinical follow-up over 18 months. The medical costs (hospitalization plus procedural costs) were calculated using a cost accounting system at the time of stent implantation and for all repeat lesion revascularizations. (At the time of writing the exchange rate was 1 Euro = 1 US dollar.) RESULTS: Because of the cost of IVUS catheters and the need for more balloons, acute procedural costs were 18% higher in the group with IVUS guidance (2934 +/- 670 Euros vs 2481 +/- 911 Euros). Clinical events (death, myocardial infarction, unstable angina or lesion revascularization) occurred in 28/76 (37%) in the group without IVUS, versus 20/79 (25%) (OR = 1.7; 95%CI = [0.82; 3.63]) in the group with IVUS. There was a higher number of revascularization procedures in the control group (31 in the control group vs 20 in the IVUS group). The cumulative medical costs at 18 months were only slightly higher in the IVUS group (4535 +/- 2020 Euros vs 4679 +/- 1471 Euros in the IVUS group), as the higher acute costs in the group with IVUS guidance were partially offset by the lower cost for revascularization procedures. Sensitivity analysis using variations of the unit costs as well as variations in the number of revascularization procedures and length of hospital stay showed that the overcost remained in a range between 1% and 7.6%. CONCLUSIONS: Over 18 months of followup, despite higher acute costs, IVUS optimization of stent deployment did not considerably increase the medical costs.