Goals: Chickenpox is a benign disease that affects mostly children, showing an incidence rate of 2,37% in Portugal (2005). Despite the fact that it is a self-limited disease, it is highly contagious and can have complications in 5-10% of all affected bindividuals. The aim of this work is to review the existing evidence about the benefits of using acyclovir in chickenpox treatment in the immunocompetent pediatric population, concerning symptoms, days of illness and complications. Data sources: Medline, evidence-based medicine sites, the Portuguese Medical Magazines Index (RMP) and bibliographic references of the selected articles. Review methods: Research of systematic reviews (SR), meta-analysis (MA), randomized controlled trials (RCT) and guidelines (G), using the key-words: chickenpox and acyclovir. SORT taxonomy was used to present the results. Results: 105 articles were found, 11 of which were selected: two SR, three RCT and six G. SR and RCT analysis show that the use of oral acyclovir in chickenpox treatment is associated with a reduction of the number of days of fever and the maximum number of lesions. These are small effects that are only present when the medication is started during the first 24h of rash. There are no clinically important differences concerning chickenpox secondary complications between the acyclovir and placebo treatment. Consequently, the use of oral acyclovir is not routinely recommended in the immunocompetent paediatric population (Recommendation A). The guidelines are consistent with this recommendation. Conclusions: Apart from the modest effects of acyclovir in symptoms improvement, the need for an early administration of this medication, as well as its posology, turns difficult its use. Further studies are needed to evaluate acyclovir cost-benefit relation, and the safety and efficacy of other antiviral drugs in children.