Objectives and Background: We sought to evaluate whether quantified calcium contents of chronic total occlusion (CTO) on Multi-detector computed tomography (MDCT) correlate with immediate procedural outcome. Methods: A total of 115 patients with CTO lesions underwent 64-slice MDCT prior to percutaneous coronary intervention (PCI) were analyzed. The lesions were divided into 2 groups according to procedural outcomes (79 patients with PCI success in group 1, 36 lesions with PCI failure in group 2). Clinical, angiographic and MDCT parameters including lesion length, vessel area (VA), calcium area (CA) and % CA/cross section area(CSA) in 5mm at proximal cap (proximal segment), the most calcified lesion in CTO lesion and 5mm at distal cap (distal segment) were elucidated and compared between the two groups. Results: Total procedural success rates were 69% (79 of 115 patients). Baseline characteristics between two groups were not significantly different. By angiography, tapered stump was seen more in Group 1 than in Group 2 (84% vs 30%, p=0.001) and calcification at stump was observed more in Group 2 than in Group 1 (30% vs 76%, p=0.001). Measured by MDCT, lesion length were longer in Group 2 than that of Group 1 (24.5 vs 38.7 mm). In proximal segment, VS, CA and % CA/CSA were not significantly different, but in severe segment, these parameters were larger in Group 2 than those in Group 1. In distal segment, CA were larger in Group 2 than that in Group 1. Conclusion: Regional calcium assessment, especially in severe CA, can be useful to predict procedural outcome in PCI of CTO and MDCT may be useful for pre-procedural strategy of recanalization for CTO.