Technical Abstract: The objectives of the study were to obtain information about the relationship between cardiovascular and diabetic risk factors of mothers and their children and to determine whether these relationships differ by physical activity or ethnicity. Prospective study. The Texas site of the Studies of Child Activity and Nutrition Program. A 1986 to 1989 triethnic sample (European American, African American, and Hispanic) of 133 mothers and their 6- to 7-year-old children. Maternal and child fasting insulin levels; total, high-density lipoprotein, and low-density lipoprotein cholesterol levels; triglyceride levels; waist circumference; systolic and diastolic blood pressures; height; weight; and body mass index. Maternal physical activity was assessed by means of a 7-day recall. Child physical activity was assessed by heart rate monitoring. Correlational methods were used to describe the relationships among metabolic risk factors and physical activity; chi2 tests of independence were used to examine the relationships between ethnic groups. Results showed that the body mass index and waist circumference were significantly (P<.05) associated among Hispanic mothers and their children, but not in other ethnic groups. Insulin, high-density lipoprotein, and low-density lipoprotein levels were significantly associated among African American mothers and their children, but not in other ethnic groups. Maternal and child physical activity were not significantly associated with any of the risk variables or each other. In conclusion, the relationships between the risk factors of mothers and children differed by ethnicity, but not by physical activity.