It is not known to what extent exercise programs increase maximal oxygen uptake (VO(2max)) in patients with coronary heart diseases (CHD). The purpose of this study is to determine the effect of exercise interventions on VO(2max) in subjects with CHD. Database search of randomized controlled trials was conducted from PubMed. Studies were included that reported the characteristics and effects of exercise interventions in subjects with CHD, included a non-exercise control group and measured VO(2max) using direct measurement method. Eighteen studies were eligible. Exercise interventions increased VO(2max) by 2.6 +/- 1.6 and 0.3 +/- 1.4 mL/kg/min in the training and control groups, respectively. The net difference in the change of VO(2max) between the groups was 2.3 mL/kg/min with a standardized mean difference of 0.60 [95% CI 0.47, 0.74] (P<0.001). Aerobic training led to a larger difference in VO(2max) between the groups than other training modes. Over 6 months of training period and training started within 3 months after a cardiac event also had a significant effect on VO(2max). This analysis showed that a long exercise training period starting soon after a cardiac event improved VO(2max) in patients with CHD most effectively. In future studies, the training programs should be designed carefully as even larger improvements in VO(2max) may be possible.