Objectives: Changes of ruptured plaques in nonculprit lesions were evaluated using coronary angioscopy. Background: The concept of multiple coronary plaque ruptures has been established. However, no detailed follow- up studies of ruptured plaques in nonculprit lesions have yet been reported. Methods: Forty- eight thrombi in 50 ruptured coronary plaques in nonculprit lesions in 30 patients were identified by angioscopy. The percent diameter stenosis(% DS) at the target plaques on quantitative coronary angiographic analysis and the serum C reactive protein(CRP) level were measured. Results: The mean angioscopic follow- up period was 13± 9 months. Thirty- five superimposed thrombi still remained at follow- up, and the predominant thrombus color changed from red(56% ) at baseline to pinkish- white(83% ) at follow- up. The healing rate increased according to the angioscopic follow- up period(23% at ≤ 12 months vs. 55% at >12 months, p=0.044). The % DS at the healed plaque increased from baseline to follow- up(12.3± 5.8% vs. 22.7± 11.6% , respectively; p=0.0004). The serum CRP level in patients with healed plaques(n=10) was lower than that in those without healed plaques(n=19; 0.07± 0.03 mg/dl vs. 0.15± 0.11 mg/dl, respectively; p=0.007). Conclusions: The present study demonstrated that: 1) ruptured plaques in nonculprit lesions tend to heal slowly with a progression of angiographic stenosis; and 2) the serum CRP level might reflect the disease activity of the plaque ruptures. Objectives: Changes of ruptured plaques in nonculprit lesions were evaluated using coronary angioscopy. Background: The concept of multiple coronary plaque ruptures has been established. However, no detailed follow- up studies of ruptured plaques in nonculprit lesions have yet been been reported. Methods: Forty - eight thrombi in 50 ruptured coronary plaques in nonculprit lesions in 30 patients were identified by angioscopy. The percent diameter stenosis (% DS) at the target plaques on quantitative coronary angiographic analysis and the serum C reactive protein (CRP) level were measured. : The mean angioscopic follow- up period was 13 ± 9 months. Thirty- five superimposed thrombi still remained at follow-up, and the predominant thrombus color changed from red (56%) at baseline to pinkish- white (83%) at follow The% DS at the healed plaque increased from (23% at ≤ 12 months vs. 55% at> 12 months, p = 0.044) - up. The healing rate was increased according to the angioscopic follow- up period The serum CRP level in patients with healed plaques (n = 10) was lower than that in those without healed plaques (n = 10) 19; 0.07 ± 0.03 mg / dl vs. 0.15 ± 0.11 mg / dl, respectively; p = 0.007). Conclusions: The present study demonstrates that: 1) ruptured plaques in nonculprit lesions tend to heal slowly with a progression of angiographic stenosis; and 2) the serum CRP level might reflect the disease activity of the plaque ruptures.