Objective: The effects of coronary artery bypass grafting (CABG) on mortality have not been evaluated in patients with well-developed coronary collaterals. We investigated functional capacity, presence of angina, the occurrence of acute myocardial infarction, survival and mortality in patients with well-developed coronary collaterals both undergoing and refusing CABG. Methods: The study was designed as a retrospective observational case-controlled study. Seventy-eight patients undergoing coronary angiography were included in this study. They had critical occlusion in the proximal left anterior descending artery (LAD) with Rentrop-3 collateral circulation towards LAD, and to proceed with CABG has been suggested. The patients were divided in two groups; first group proceeding with CABG (n=40) and the second, rejecting the surgery (medical treatment group; n=38). The rates of survival, the incidence of angina pectoris and acute myocardial infarction as well as the functional capacities were evaluated in all patients. Survival rates were evaluated using Kaplan-Meier survival analysis. Results: No statistically significant difference was observed between the two groups regarding the baseline characteristics of patients, the presence of angina pectoris, the severity of angina pectoris according to CCS, the occurrence of acute myocardial infarction or stroke, and the functional capacity according to NYHA (p>0.05). Death due to cardiovascular reasons was observed in eight patients of CABG group and in five patients of medical treatment group (p=0.710). The 5-year survival rate was observed to be 80% in CABG group while it was observed to be 84% in the medical treatment group (p=0.730). Conclusion: There was no significant difference regarding the survival rates in patients with well-developed coronary collaterals proceeding with CABG or medical treatment. (Anadolu Kardiyol Derg 2012; 12: 97-101) Key words: Coronary collateral circulation, coronary bypass surgery, survival analysis, prognosis 97 ÖZET Amaç: Bugüne kadar, iyi gelişmiş koroner kolaterali olan hastalarda baypas cerrahisinin mortalite üzerine etkisi değerlendirilmedi. Biz iyi geliş-miş kolaterali olan, baypas olmuş ve baypas'ı reddeden hastalar arasında sağkalım, mortalite, fonksiyonel kapasite, angina varlığı ve akut miyokart enfarktüs gelişimini araştırdık. Yöntemler: Çalışma retrospektif, vaka-kontrollü gözlemsel bir çalışma olarak dizayn edildi. Koroner anjiyografi uygulanan, sol ön inen arter proksimalinden tam tıkalı olup, Rentrop-3 kolaterali olan ve baypas ameliyatı önerilen 78 hasta retrospektif olarak çalışmaya alındı. Hastalar baypas'ı kabul eden (Grup1, n=40) ve reddeden (Grup 2, n=38) hastalar olmak üzere iki gruba bölündü. Tüm hastalarda sağkalım, fonksiyonel kapasite, angina varlığı ve akut miyokart enfarktüs gelişimi araştırıldı. Sağkalım oranları Kaplan-Meier sağkalım analizi ile değerlendirildi. Bulgular: İki grup arasında hastaların temel özellikleri, angina varlığı ve şiddeti, fonksiyonel kapasite, akut miyokart enfarktüsü veya inm...