Total body irradiation regimen (TBI) or intravenous busulfan regimens (BU) are the most widely used myeloablative conditioning regimens for allotransplants. Despite its increasing use, their actual prescription ratio is unknown in Japan. The Diagnosis Procedure Combination (DPC) is a case-mix classification system that is linked with a lump-sum payment system for inpatient care reimbursement in Japan nationwide sample database. This research aims to investigate if the patient selection and prescribing patterns to extracting the DPC data can assess real-world outcomes comparing between BU and TBI prescription trend with myeloid malignancies. This study was a retrospective database study. To adjust bias of treatment choice by hospitals, regression model was used to predict new BU rate, starting with age, square of age, Acute myeloid leukemia(AML) vs Myelodysplastic syndromes(MDS), source of SCT including Allogeneic bone marrow stem cell (BMT), Allogeneic peripheral blood stem cell (PBSCT) and Umbilical cord blood(CBT), and dummy functions of each hospitals. By multiplying acquired each coefficients and explanatory variables of each patients and relationship between adjusted BU rate and age was obtained. A total of 647 patients prescribed BU, and a total of 1,122 patients prescribed TBI as conditioning regimen in the DPC data between April, 2013 and March, 2014.Patients (diagnosed AML 74%, MDS 26%) received BU were older (median age 53 years, 45%>55 years) than patients (diagnosed AML 80%, MDS 20%) received TBI (median age 45 years, 28%>55 years). Stem cell source were BMT 53%, PBSCT 34%, CBT 17% for BU, BMT 45%, PBSCT 21%, CBT 37% for TBI. BMT were more chosen to patients who received TBI than patients who received BU (P<0.05, Fisher). Our research, real-world data, showed prescription trend was still TBI preferable in Japan. Regarding particular ages, such as infants, and elderly people, BU tended to use selectively.