p53 upregulated modulator of apoptosis (PUMA) is a recently identified p53 target gene which can induce apoptosis. Compared with other p53 target genes, p53 has two important characteristics. One is that PUMA almost mediates all p53-dependent apoptotic signals. The other is that PUMA is not only required for p53-dependent apoptotic pathway, but also for p53-independent apoptotic pathway. That means although PUMA is p53 target gene, it is also necessary for p53-independent apoptosis. In cardiomyocytes, PUMA is involved in apoptosis induced by various stimulations such as ischemia/reperfusion, endoplasmic reticulum stress. Therefore, PUMA plays a pivotal role in cardiomyocyte apoptosis.