We examined the association between leisure-time physical activity (LTPA) and metabolic syndrome (MetS) among 4,665 randomly selected adults who participated in the Tehran Lipid and Glucose Study, 2005-2008. Normal-weight participants with light LTPA had higher risk of low high-density lipoprotein cholesterol and elevated levels of triglycerides than those with vigorous LTPA. Overweight adults with moderate LTPA had higher risk of having elevated levels of fasting blood glucose than adults with vigorous LTPA and, in the same group, we found an inverse association between light LTPA and MetS after adjustment for sex, age, education levels, smoking, and calorie intake. Although participants in the normal-weight and obese groups with vigorous LTPA had higher risk of high systolic blood pressure than participants with moderate LTPA, this finding had no clinical significance. Increased LTPA is associated with decreased risk of any damaging changes in the markers of MetS.