Increased triglycerides (TG) and decreased high-density lipoprotein (HDL) cholesterol are key metabolic abnormalities in patients with insulin resistance (IR) states, including diabetes mellitus. The TG/HDL cholesterol ratio was advocated as a simple clinical indicator of IR, but studies yielded inconsistent results. The total cholesterol/HDL cholesterol ratio was widely used to assess lipid atherogenesis, but its utility for assessing IR or its associated coronary heart disease (CHD) risk was unknown. TG/HDL cholesterol and total cholesterol/HDL cholesterol ratios were related to IR (top quartile of the homeostasis model assessment-IR) in 3,014 patients (mean age 54 years; 55% women). Logistic regression was used to construct receiver-operator characteristic curves for predicting IR, with lipid ratios as predictors. Multivariable Cox regression was used to evaluate whether adjusting for lipid ratios attenuated the association of IR with CHD. Cross sectionally, age- and gender-adjusted correlations of IR were 0.46 with TG/HDL cholesterol ratio and 0.38 with total/HDL cholesterol ratio. IR prevalence increased across tertiles of lipid ratios (p <0.0001). The area under the receiver-operator characteristic curves for predicting IR with TG/HDL cholesterol ratio was 0.745, slightly higher than that for total/HDL cholesterol ratio (0.707; p <0.001 for comparison). On follow-up (mean 6.4 years), 112 patients experienced initial CHD events. IR was associated with CHD risk (multivariable-adjusted hazards ratio 2.71, 95% confidence interval 1.79 to 4.11), which remained significant even after adjustment for lipid ratios. In conclusion, our observations suggested that the TG/HDL cholesterol ratio was an imperfect surrogate for IR and its associated CHD risk, and it was only slightly better than the total/HDL cholesterol ratio for this purpose.