High-dose methotrexate (HDMTX) : antimetabolite that interferes with the metabolism of folic acid, inhibiting the dihydrofolate reductase (DHFR).. Approximately 2 to 10% of patients receiving HDMTX  suffer Acute Kidney Injury, despite appropriate supportive care measures during HDMTX administration. Prolonged renal impairment systemic methotrexate exposure Monocentric longitudinal study, data collected over 9 years. Population: Only adult patients with a hematological indication were included. Endpoints :-Determine covariates that may influence patient exposure to HDMTX-Identify covariates associated with increased toxicities Database  generated in Microsoft Office Excel by collecting datas using softwares available at APHM (Axigate, Pharma, Chimio…) Data Treatment : 1) Datas in excel format (.xlsx) converted in .csv format to be analyzed with R software. 2) Script redacted in R with some covariates recoded 3) Script ok  exploratory data analysis