To determine the prognostic role of triglyceride (TG) to high-density lipoprotein cholesterol (HDL) ratio for poorly developed coronary collateral circulation (CCC) in elderly patients with ST-segment elevation myocardial infarction (STEMI) and acute total occlusion (ATO). As a retrospective case-control study, elderly patients (age >= 60 years) with both STEMI and ATO (n=346) were classified as having either poorly- or well-developed CCC (Rentrop grades 0-1 and 2-3, respectively). The ratio of TG/HDL was calculated according to the detected levels of TG and HDL. The difference of TG/HDL ratio in those 2 groups was compared by Student t test, and multivariate logistic regression analysis indicating occurrence of poorly developed CCC was performed. Receiver operator characteristic curve (ROC) analysis of TG/HDL ratio which determine the optimal cut-off value of TG/HDL ratio was applied. The TG/HDL ratio was significantly higher in patients with poorly developed CCC than in those with well-developed CCC (2.88 +/- 2.52 vs 1.81 +/- 1.18, P<.001). In multivariate logistic regression analysis, higher TG/HDL ratio (OR 1.789, 95% CI 1.346-2.378, P<.001) and the presence of left circumflex branch of coronary artery (LCX) occlusion (OR6.235, 95% CI 2.220-17.510, P=.001) were emerged as independent positive predictors of poor development of CCC, whereas presence of right coronary artery (RCA) occlusion (OR 0.474, 95% CI 0.265-0.850, P=.002) and onset time (OR 0.693, 95% CI 0.620-0.775, P<.001) were found as negative indicators. The optimal cut-off value of TG/HDL ratio was found as 1.58 in ROC analysis, which yielded an area under the curve value of 0.716 (95% CI 0.654-0.778, P<.001) and demonstrated a sensitivity of 80.9% and a specificity of 59.3% for prediction of poorly developed CCC. TG/HDL ratio is an independent risk factor for predicting poor development of CCC in elderly patients with STEMI and ATO.