Cardiovascular event and infection are leading causes of death from peritoneal dialysis (PD). This study examined in vitro cellular mechanism for cardiotoxicity induced by PD-related peritonitis. Cultured human cardiomyocytes were treated with PD effluent (PDE) during peritonitis (PPDE), and effects of PPDE on cultured cardiomyocytes in terms of apoptosis, with expression its related genes assessed. Results showed PPDE treatment of cardiomyocyte leading to onset of apoptosis, as confirmed by phosphatidylserine exposure plus DNA fragmentation and damage. This apoptosis is mediated by reduced Bcl-2/Bax and Bcl-x(L)/Bax ratios, as well as reduced expression of GATA-4, an important cardiomyocyte survival factor, at the level of transcription. These changes activated pro-apoptotic pathways. PPDE treatment also inhibited ERK signals, contributing to cardiotoxicity. Our findings revealed that PPDE contains potent pro-apoptotic factors that regulate expression of GATA-4 and Bcl-2 families, inducing cultured cardiomyocyte apoptosis. This pinpoints a key role of apoptosis in PD-associated cardiovascular events, along with a potential therapeutic target.