Varicella may have a serious and sometimes fatal course, especially in immunocompromised patients. Some patient groups may need prophylaxis after exposure to the varicella-zoster-virus. In this article we review the evidence for usefulness of prophylactic measures after such exposure.The article is based on a non-systematic literature search in Medline, the Cochrane Library, UpToDate and Clinical Evidence.The effect of post-exposure varicella prophylaxis on disease rate and severity of varicella is only weakly documented. There is some evidence that passive immunisation with varicella-zoster immunoglobulin (VZIG) reduces the risk of serious disease when it is administered within 72-96 hours after exposure. Several studies of mostly healthy children have shown that prophylactic acyclovir is better than control treatment, but the studies are small and they are not properly designed. Post-exposure vaccination is shown to reduce disease rate and severity in otherwise healthy children.We believe that acyclovir or valacyclovir can be used as post-exposure varicella prophylaxis in risk patients for whom the time window for VZIG-use has expired.