We examined the impact of metabolic syndrome (MS) on coronary stenosis progression and major cardiovascular (CV) events and investigated the mitigating effects of low-density lipoprotein (LDL) cholesterol lowering and LDL cholesterol lowering plus high-density lipoprotein (HDL) cholesterol increasing. This analysis combined individual patient data from 445 subjects who participated in 3 double-blinded, randomized, placebo-controlled trials (FATS, HATS, and AFREGS) comparing intensive lipid therapy to placebos on coronary stenosis progression by quantitative coronary angiography and on major CV events. The primary end points were change in mean proximal coronary diameter stenosis (Delta%S(prox)) over 3 years and the frequency of the predefined composite of coronary artery disease death, nonfatal myocardial infarction, stroke, and revascularization due to worsening ischemia. Patients with MS had 50% more rapid coronary stenosis progression and 64% increased CV event frequency compared to those without. More rapid coronary stenosis progression was significantly and independently associated with a 3.5-fold increased event risk (p <0.001). Combination lipid therapy significantly decreased stenosis progression by 83% (Delta%S(prox) 0.5 vs 2.9, p <0.001) in patients with MS and induced a small net regression in those without (Delta%S(prox) -0.3 vs 2.0, p <0.001). Combination therapy decreased the event rate by 54% (13% vs 28%, p = 0.03) in those with MS and by 82% (3% vs 17%, p = 0.002) without. On average, each 10% decrease in LDL cholesterol or 10% increase in HDL cholesterol was significantly associated with a 0.3 Delta%S(prox) decrease. Each 10% decrease in LDL cholesterol or 10% increase in HDL cholesterol was associated with 11% (p = 0.02) or 22% (p <0.001) event risk decrease. In conclusion, patients with MS have significantly more rapid coronary stenosis progression and a higher frequency of CV events. Greater stenosis progression rate is associated with a higher event rate. LDL cholesterol-lowering and HDL cholesterol-increasing therapies independently and significantly decrease coronary stenosis progression and decrease CV events.