A meta-analysis of 5 randomized controlled trials (RCT), involving 339 patients with acute infectious mononucleosis (IM) treated with acyclovir (ACV) was performed. ACV was given intravenously in 2 RCTs, which included patients with more severe disease, and orally in the remaining 3 RCTs, which included patients with mild to moderate IM. Both clinical and virological endpoint data available from RCT were evaluated in this study. There was a trend towards clinical effectiveness of ACV treatment, but no statistically significant results were achieved. In contrast, a significant reduction in the rate of oropharyngeal EBV shedding was observed at the end of the therapy (overall OR: 6.62; 95% CI: 3.56-12.29; p<0.00001). However, no difference in EBV shedding was observed 3 weeks later. There was no significant difference on adverse events in the groups of patients treated with ACV or placebo. In conclusion, clinical data do not support use of ACV for the treatment of acute IM, despite good virological activity of this drug. There is a need for more effective treatment of EBV infection.