Abstract: Objective To observe the efficacy and major adverse reactions of a novel total body irradiation（TBI） with an intensity-modulated radiation therapy（IMRT） technique. Methods Fifteen patients who underwent a TBI therapy as a preconditioning regimen of hemapoietic stem cell transplantation（HSCT） at the BenQ Medical Center， between August 1st， 2012 and January 31st， 2015， were recruited in this study. TBI used fractionated radiotherapy and IMRT technique，and EclipseTM Treatment Planning System was employed to perform treatment planning. The clinical target volume（CTV） contained total narrow， main lymphatic chains， testis and spleen and the external expansion on the CTV（3 mm） was defined as planning target volume. In this study， the TBI total dose was up to 12 Gy， 2 Gy twice a day for 3 days. Results With a median follow-up of 17 months（range 1-30 months）， neutrophils of 13 patients（13/15）had increased， and up to 0.5×109/L in 9-32 days after transplant， and the absolute number of platelet was over 20×109/L in 12-37 days postransplant. Meanwhile， PCR analyze also showed a donate karyotype， indicating a successful therapy. Except one suffered a severe（grade 3） radiation enteritis， patients receiving TBI therapy had mild and tolerable adverse reactions， including oral mucosal injury and mild diarrhea. Conclusion TBI with fractionated radiotherapy and IMRT technique is useful as a HSCT pretreatment in clinic， while limited to the short observation period， the long-term efficacy and adverse reactions remains to be studied.