AIM: To study apoptosis in heart of multiple organ dysfunction syndrome (MODS) rat at high altitude. METHODS: The two-hit model of MODS rat was used at two different altitude(1 510 m, 3 900 m). Hemorrhage was induced in Wistar rats by catheterizing the femoral artery until a mean arterial pressure was 35 mmHg and maintained for 1 hour. Rususcitation was performed with lactated Ringer′s solution at 24 h after hemorrhage, cecal ligation and puncture(CLP) was performed .Then rats were killed at 3 h,6 h,12 h and 24 h after CLP, and myocardium sample was excised and stored in liquid nitrogen. Apoptosis in heart was determined by DNA agarose gel electrophoresis, flow cytometry(FCM), transmission electron microscope(TEM) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL). RESULTS: The special ladder pattern for apoptosis was seen in myocardium sample at high altitude(3 900 m) group.The apoptotic rate in myocardium was higher in high altitude(3 900 m) group than that in lower altitude(1 510 m) group( P