The effect of a 4-month exercise program on measures of cardiovascular disease (CHD) risk was observed in women (mean age = 59.2 +/- 3.9 years) of postmenopausal years with NIDDM, who demonstrated fair to normal control of blood glucose control. The women were randomly assigned to either an exercise (n = 5) or control (n = 5) group. Initially, both groups had a similar body mass index, resting heart rate and blood pressures, blood glucose and hemoglobin A1. After 4 months, the exercise group demonstrated a 32% increase (P less than 0.03) in both absolute and relative maximum oxygen uptake (VO2) while the control group remained unchanged. Significant differences were found between the exercisers and non-exercisers for absolute (F(1,8) 4.94, P = 0.057) and relative (F(1,8) 7.67, P = 0.024) maximum VO2 from pretest to posttest. Body weight (kg) and body fat (%) remained unchanged for both groups. Although total cholesterol was found to be reduced by 13% for the exercise group (P less than 0.03) and 11% for the controls (P less than 0.01), a 15% decrease (P less than 0.03) in high-density lipoprotein (HDL) was observed for the control group, only. Hence, a marked difference (P less than 0.03) in the risk ratio was observed between the exercise and control groups. These data suggest that physical exercise may play an important role in the maintenance of HDL mass and in the reduction of CHD risk factors in women of postmenopausal years with NIDDM.