Introduction: Ischemic cardiomyopathy (ICM) and idiopathic dilated cardiomyopathy (DCM) share common structural alterations with a high mortality from sudden cardiac death (SCD) and pump failure. Implantable cardioverter-defibrillator (ICD) has, since inclusion in international guidelines, been confirmed beneficial and cost-effective for primary prevention of SCD in patients with ICM, while huge debates in non-ischemic heart disease. This study was to compare the primary prophylactic value of ICD therapy in patients with ICM or DCM to identify a subgroup with greater advantage specially. Methods: We conducted a retrospective, single-center study, which enrolled 82 patients with ICM or DCM and guideline indications for primary prophylactic ICD or cardiac resynchronization therapy-defibrillator (CRT-D). Primary end-point was all-cause mortality and secondary outcomes included SCD and cardiovascular death. Results: During a median follow-up of 38.5 months, 78 patients baseline data were analyzable. The primary outcome occurred in 8 patients in ICM group and 5 patients in DCM group (p = 0.012). Cardiovascular death occurred in 5 patients in ICM group and 3 patients in DCM group [hazard ratio (HR) 0.119, 95% confidence interval (CI) 0.016-0.860, P = 0.035]. Resuscitated cardiac arrest or sustained ventricular tachycardia occurred in 4 patients in ICM group and 8 patients in DCM group (HR 0.294, 95% CI 0.040-2.144, P = 0.227). Conclusions: DCM patients with ICD implantation could gain more benefit with a reduction in the risk of all-cause mortality and cardiovascular disease compared with ICM patients, while the occurrence of SCD had no difference in two groups.