With its broad spectrum of activity and better tolerability profile than conventional amphotericin B, liposomal amphotericin B (L-AmB) may be the drug of choice for antifungal prophylaxis in haematological patients. An open-label, multicentre, prospective, pilot study was conducted in adult patients receiving chemotherapy for acute leukaemia (AL) or myeloablative allogeneic stem cell transplantation (SCT). Patients received weekly 10mg/kg infusions of L-AmB for 4 weeks for AL and 8 weeks for SCT. The primary objective was safety, with particular attention to infusion-related reactions and nephrotoxicity. Twenty-nine adult patients were included: 21 AL (median age 52 years) and 8 SCT (median age 37 years). The most frequent adverse events (AEs) related to study drug were infusion-related reactions, 12 of which (from a total of 76 infusions) led to increased infusion duration for better tolerance. No AE related to the study drug led to discontinuation of prophylactic treatment in AL patients. In SCT patients, eight AEs (in six patients) reported to be related to study treatment led to treatment discontinuation. Enrolment was discontinued in the SCT group as recommended by the independent data review committee in accordance with the 10% limit of AEs (CTC grade 3-4) fixed by the protocol. The appropriate timing of high-dose prophylactic L-AmB remains to be determined in the SCT setting to optimise the safety profile of this regimen. For AL, a 10mg/kg weekly dose appears to be well tolerated during chemotherapy and may represent an important tool towards improving AL patient outcome.