To study the impact of diet and exercise and the combination thereof on cardiovascular risk factors, 157 healthy men aged 35-60 years (mean +/- S.D.; 46.2 +/- 5.0) with slightly to moderately raised cardiovascular risk factors, were randomized to 4 groups, diet (D, n = 40), exercise (E, n = 39), diet plus exercise (DE, n = 39), and no active intervention (controls (C, n = 39)), and investigated at baseline and after 6 months. BMI was significantly reduced in Groups E and DE (mean difference and 95% confidence intervals (CI), -0.3 (-0.5, -0.01) and -0.6 (-0.9, -0.3) kg/m2, respectively). Waist circumference was reduced in all 3 intervention groups (D, E, and DE), -1.3 (-2.5, -0.1), -2.2 (-3.2, -1.3) and -3.0 (-3.9, -2.0) cm, but not in the control group. Blood pressure (BP) was reduced in all 3 intervention groups, systolic BP 4-7 mmHg and diastolic BP 2-6 mmHg. Serum cholesterol was reduced in Group DE, -0.45 (-0.77, -0.13) mmol/l. VLDL-cholesterol was reduced in Groups E and DE, -0.14 (-0.26, -0.03) and -0.09 (-0.18, -0.01) mmol/l, whereas LDL-cholesterol was reduced in Groups D and DE -0.30 (-0.54, -0.06) and -0.35 (-0.64, -0.05) mmol/l. In contrast, neither HDL-cholesterol nor serum triglycerides were influenced by the interventions. According to the coronary risk profile derived from the Framingham study, all 3 intervention groups (D, E, and DE) significantly reduced their estimated 10-year risk (-13, -12, and -14%, respectively). We conclude that even with rather moderate changes in diet and exercise, several important cardiovascular risk factors can be affected and that diet and exercise were about equally effective in reducing cardiovascular risk.