An expansion of large granular lymphocytes (LGL) in the peripheral blood (PB) of a 10-year-old child is described. After a long history of uncertain hematological diagnosis and chemotherapeutic regimens and 2 years after any kind of therapy, the child showed in PB an expansion of LGL E-rosette+, OKT3+, OKT8+, Leu7+. Cytotoxic activities showed high natural killer activity and an increase of PHA-induced cytotoxicity. Histological findings in the spleen, abdominal lymph nodes and bone marrow excluded a lymphoproliferative disease, but liver biopsy revealed a chronic aggressive hepatitis.