Background: The Metricath��� system consists of a low-pressure (260 mmHg. 1/3 ATM) balloon catheter connected to a pressure transducer and infusion pump linked to a console that records pressure-volume curves to measure the cross sectional area (CSA) and diameter. The Metricath��� System acquires measurements in approximately 30 seconds and allows multiple measurements with the same catheter. Animal tests have shown that Metricath is equivalent to intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA) in stented arteries. Methods: We compared diameter and CSA measurements by Metricath, IVUS, and QCA at spots of 1.8 - 3.6 mm reference vessels (pre stent) and stented vessels. Intracoronary injection of nitroglycerine was given prior to insertion of the catheters. Results: Comparison of diameter measures at 15 spots showed no significant differences among the three methods (mean diameter 짹 SD, 2.75 짹 0.40 mm, 2.87 짹 0.23 mm and 2.88 짹 0.26 mm) of QCA, IVUS and Metricath, respectively. Linear regression analysis showed excellent correlation between measurements (r=0.95 between Metricath and QCA or IVUS). Comparison of CSA at 9 spots showed no significant differences between Metricath and IVUS (mean CSA 짹 SD, 6.52 짹 1.55 mm짼 and 6.38 짹 1.38 mm짼, respectively). Linear regression analysis showed excellent correlation between Metricath and IVUS (r=0.97). No complications were noted and no difficulties were encountered when crossing the lesion with the balloon. Conclusions: The Metricath has a good correlation with QCA and IVUS for the measurements of the diameter and CSA of pre and post stented coronary arteries. The Metricath��� system may have an alternative role to replace high-cost IVUS guidance during coronary stenting.