CMV related matrix protein pp65 antigenemia was screened in 100 Allo HSCT patients after transplantation. As control groups, samples from fourteen autologous HSCT patients, seventeen patients with various hematological malignant disorders, as well as twenty seven normal donors also were detected. CMV antigenemia was found in 91/100 Allo HSCT patients (91%) after transplantation. 56 % patients with antigenemia developed CMV disease. 54% patients developed acute GVHD. In 87 patients survived more than three months, 52 9% patients developed chronic GVHD. After follow up 18(4～36) months post transplantation, 21 patients died of CMV related diseases. Compared with autologous and non transplantation patients, CMV antigenemia and CMV diseases were particularly associated with Allo HSCT patients. It was obviously correlated with acute and chronic GVHD. CMV infection is a major factor affecting the clinical outcome of Allo HSCT patients.