Background Despite its widespread use in the management of HIV-related cytomegalovirus (CMV) infection, there have been surprisingly few reports of the use of valganciclovir (VGC) in the post-allotransplant setting.So far, no multi-center, non-crossover trial data have been available with the use of this drug as the primary pre-emptive.The present study evaluated the efficacy and safety of VGC for preemptive therapy of CMV infection after allogeneic hematopoietic stem cell transplantation (HSCT).Methods From January to April 2007, VGC was adopted in eleven centers in mainland China for pre-emptive therapy of CMV infection in consecutive patients undergoing allogeneic HSCT.Allogeneic HSCT recipients were followed weekly via CMV pp65 antigenemia assay or real-time quantitative polymerase chain reaction (PCR) for detection of CMV-DNA.Patients with a positive assay were treated with VGC, 900 mg P.O.twice a day for 14 days followed by 900 mg P.O.once a day for 14 days after a negative result or the CMV-DNA load was lower.Results A total of 54 patients (15 siblings, 28 mismatched related donors, 11 unrelated donors) had a positive assay treated with oral VGC.The seroconversion rate was 89% (48/54) as confirmed by a negative assay; six patients failed oral VGC.No significant toxicity was encountered.No case of CMV disease was diagnosed in the responding patients with a median follow-up of 5.3 months after the drug administration.Conclusion Pre-emptive therapy of CMV viraemia with oral VGC is safe and effective in allogeneic HSCT.