We describe an immunocompetent 12-year-old boy with chronic EBV infection and lymphoid interstitial pneumonitis. Lymph node biopsies showed effacement of the architecture with polymorphic cellular infiltrates, consisting predominantly of T cells and natural killer cells. No clonal rearrangement of TCR or immunoglobulin genes was seen. DNA was extracted from hilar lymph nodes; sequencing of the carboxy terminal region of the latent membrane protein 1 (LMP-1) oncogene revealed a 69 base-pair deletion and four point mutations. Immunosuppressive treatment with prednisone and cyclosporine reversed the lymphadenopathy.