[Background] Our previous data demonstrated that hydrogen (H₂) inhalation improved cardiac function in a rat model of cardiac arrest. In this study, we examined the genes expression of post-cardiac arrest treated with H₂ using a DNA microarray based comprehensive approach. [Methods and results] Rats were subjected to 6 minutes of ventricular fibrillation cardiac arrest followed by cardiopulmonary resuscitation. Resuscitated rats were mechanically ventilated with 26% O₂ with or without 1.3% H₂. Sham-operated rats had the same operative procedure without cardiac arrest. Animal survival rate on day 7 was 38.4% (control group) vs. 71.4% (H₂ treated group). We isolated hearts on 7 days after resuscitation, and then analyzed gene expression using a DNA microarray. One hundred fifty-one genes were up-regulated while 109 were down-regulated genes in cardiac arrest rats. In addition, 511 genes were increased and 461 genes were decreased in H₂ treated group than those of the untreated group. Hierarchical clustering algorithm also showed  obvious differences in comprehensive gene expressions between the untreated and H₂ treated group. [Conclusion] Our data demonstrated that H₂ inhalation on post-cardiac arrest syndrome.