['Oxidized low-density lipoprotein (oxLDL) levels have been found to play an important role in the progression of atherosclerosis. However, methods for effectively reducing oxLDL levels have not been established. Comprehensive cardiac rehabilitation (CR) with exercise training prevents the progression of atherosclerosis, and might reduce oxLDL levels. METHODS\u2004AND\u2004RESULTS: We measured the serum levels of malondialdehyde-modified LDL (MDA-LDL), a marker of oxLDL, in 136 patients who were enrolled in a 6-month CR program. Peak oxygen consumption (V̇O2) and MDA-LDL levels were analyzed, before and 6 months after enrolment. In total, 67 patients completed the CR program (CR group) and 69 patients failed to complete the program (non-CR group). Peak V̇O2increased significantly in the CR group (P<0.01). The levels of MDA-LDL decreased significantly in the CR group (P<0.01) but not in the non-CR group. ∆V̇O2(peak V̇O2after CR-peak V̇O2before CR) was negatively associated with ∆MDA-LDL (MDA-LDL after CR-MDA-LDL before CR) (R(2)=0.11, P=0.01). Multiple regression analysis showed that continuing CR was an independent determining factor for lowering MDA-LDL levels.'] Does cardiac rehabilitation reduce serum levels of oxidized low-density lipoprotein?