Severe oral mucositis is a major cause of morbidity following allogeneic hematopoietic stem cell transplantation (AHSCT). Cryotherapy, that is, the application of ice chips on the mucosa of the oral cavity during the administration of antineoplastic agents, may reduce the incidence and severity of chemotherapy-related oral mucositis. In this multicenter randomized study, we addressed whether cryotherapy during MTX administration is effective in the prevention of severe oral mucositis in patients undergoing myeloablative AHSCT. One hundred and thirty patients undergoing myeloablative AHSCT and MTX-containing GVHD prophylaxis were enrolled and randomized to receive or not receive cryotherapy during MTX administration. The incidence of severe (grade 3-4) oral mucositis, the primary end point of the study, was comparable in patients receiving or not cryotherapy. Moreover, no difference was observed in the incidence of oral mucositis grade 2-4 and the duration of oral mucositis grade 3-4 or 2-4, or in the kinetics of mucositis over time. In univariate and multivariate analysis, severe oral mucositis correlated with TBI in the conditioning regimen and lack of folinic acid rescue following MTX administration. Thus, cryotherapy during MTX administration does not reduce severe oral mucositis in patients undergoing myeloablative allogeneic HSCT. Future studies will assess cryotherapy before allogeneic HSCT.