Valganciclovir (VGCV) is considered the agent of choice after organ transplant for cytomegalovirus (CMV) prophylaxis. The purpose of this retrospective study was to determine the effectiveness and safety of a low-dose regimen after liver transplant (OLT). Eighty-five patients who underwent OLT between August 2002 and August 2004 were included. All patient data for the first 12 months after transplant were collected. Patients received VGCV 450 mg once daily for 3 months posttransplant. CMV infection was based on detection of CMV virus or viral proteins in blood. CMV disease was defined by the presence of positive antigenemia/viremia and evidence of clinical symptoms and/or tissue findings. Patients were D+R+ (54%) and D-R+ (29%), D+R-(11%) and D-R-(6%). Overall, CMV infection and disease occurred in 13% (11/85). CMV infection and disease occurred in 7% and 6%, respectively. CMV infection and disease occurred in 44% (D+R-), 13% (D+R+), 4% (D-R+) patients. The mean time to onset of CMV infection and disease was 103 days (14 to 312 days). Overall, 82% of patients received antibody therapy. The most common adverse events associated with VGCV were leukopenia (16%), thrombocytopenia (4%), anemia (<1%), and neurotoxicity (<1%). Low-dose VGCV was not an effective means to prevent CMV infection in high-risk (D+R-) patients, especially those who received antibody induction. High-risk patients may require a high-dose regimen, such as 900 mg daily, and/or a longer period of prophylaxis, and/or reduction in the use of potent antibody treatments after liver transplant.