A five-year-old boy in the acute phase of X-linked lymphoproliferative (XLP) syndrome (Duncan disease) with high fever and hepatosplenomegaly was treated successfully with high-dose methylprednisolone and VP-16 for 15 months. He had been alive for four years after diagnosis as of this writing. We recommend high-dose methylprednisolone and VP-16 in patients with XLP who have to wait for a suitable donor before bone marrow transplantation.