The present invention relates to the use of analogs of creatine, such as cyclocreatine, as antiviral agents. Analogs of creatine can be used as antiviral agents against a variety of viruses, particularly DNA viruses, such as Herpes viruses (e.g., HSV-1, HSV-2, cytomegaloviruses, Varicella-Zoster virus) and adenovirus. The invention further relates to creatine analogs including four classes of creatine analogs selected as candidate antiviral compounds: (1) creatine analogs that can be phosphorylated by creatine kinase but differ in their phosphoryl group transfer potential, (2) bisubstrate inhibitors of creatine kinase comprising covalently linked structural analogs of adenosine triphosphate (ATP) and creatine, (3) creatine analogs which can act as irreversible inhibitors of creatine kinase, and (4) N-phosphorocreatine analogs bearing non-transferable moieties which mimic the N-phosphoryl group.