The key finding of this study is the higher prevalence of EBV active infection (presence of viral genome sequences in plasma with EBV‐CA IgM positivity and/or viral genomic sequences in plasma with elevated titers of EBV‐CA IgG without EBV‐CA IgM) observed in patients with ME/CFS compared to the controls (P = .0027). This evidence concerns the gene CD40LG and myalgic encephalomeyelitis/chronic fatigue syndrome.