Maribavir (previously known as 1263W94) is a novel benzimidazole riboside compound. This drug was in phase III of clinical trial for the prevention of cytomegalovirus (CMV) infections in transplant patients, sponsored by ViroPharma. However, drug failed to demonstrate a higher efficacy rate than the placebo. Maribavir has activity against cytomegalovirus and Epstein-Barr virus (EBV), but not against other human herpesviruses. Maribavir’s mechanism of action is unique and is complex compared to the currently approved antivirals for CMV. Maribavir inhibits the viral UL97 kinase rather than the viral DNA polymerase. The UL97 kinase is important for viral DNA elongation, DNA packaging, and nuclear egress of encapsidated viral DNA. In addition, maribavir inhibits the EBV DNA polymerase processivity factor (BMRF1), reduces the level of certain EBV glycoproteins, and inhibits viral transcription. However, future work will be designed to address the interaction of MBV and BGLF4 and to evaluate the mechanisms through which maribavir downregulates viral transcripts. BGLF4 belongs to the family of conserved herpesvirus PKs, which includes HCMV UL97, HSV UL13, and HSV US3. Maribavir does need to be phosphorylated for its activity.