Low-density lipoprotein cholesterol (LDL-C) is the primary target of cholesterol lowering therapy and exercise training is regarded as a therapeutic intervention (NCEP, 2002). However, there is insufficient evidence to characterise the dose-response relationship. In particular, it is unclear whether moderate- or high-intensity exercise confers greater reductions in LDL-C. Thus, the present study was undertaken to investigate the effects of exercise intensity on LDL-C.Sixty-six inactive, non-smoking men aged 30-45 years volunteered to take part in this study and agreed not to change their dietary habits during the intervention. Fasting measures of total cholesterol, triglycerides and high-density lipoprotein cholesterol were obtained in order to estimate LDL-C (Friedewald et al., 1972). Physical fitness (maximum oxygen consumption, VO₂ max) and body fat (estimated from skinfolds) were measured in 62 normolipidaemic men before random allocation to a control group (n = 19), a moderate-intensity exercise group (three 400 kcal sessions per week at 60% of VO₂ max, n = 22) or a high-intensity exercise group (three 400 kcal sessions per week at 80% of VO₂ max, n = 21). Baseline measurements and 24-week changes were compared using a one-way ANOVA and, where appropriate, a Bonferroni post hoc test. This study was approved by the Local Research Ethics Committee. Results are reported for men who finished the study (Table). There were no inter-group differences in physical fitness, body fat or LDL-C at baseline. Twenty-four-week changes in physical fitness and body fat were significantly different in the exercise groups compared to the control group. Significant changes in LDL-C were only observed in the high-intensity exercise group compared to the control group. The exercise-induced reduction in LDL-C was greater than that attributable to biological variation (Ricos et al., 1999) and was not correlated with the change in body fat (r = -0.07). These results suggest that high-intensity exercise is required to reduce LDL-C.