Twenty-two children with hemophagocytic lymphohistiocytosis were treated with a chemotherapy regimen consisting of VP16–213, corticosteroids, and intrathecal methotrexate. A sustained clinical and biologic complete remission was obtained in 15 children and a partial remission in one child; six children died early of opportunistic infection (n = 4) or of disease progression (n = 2). Of the 16 children who were placed in first remission, 10 received maintenance chemotherapy alone, while six underwent bone marrow transplantation (HLA matched in five, HLA mismatched in one). Of the children who received chemotherapy alone, only two are in long-term remission after cessation of treatment. The remaining eight patients relapsed after a mean period of 5.4 months (range 2 to 8 months). Further treatment using the same regimen induced second remissions of short duration; death occurred after a median period of 2.3 months (range 0.5 to 6 months). A total of nine patients received allogeneic bone marrow transplantation (BMT). Among the six children transplanted in remission, four are in long-term unmaintained remission, 1 to 6 years after HLA-matched BMT. However, the relapse that occurred in one patient 1 year post BMT is difficult to interpret because the donor, the patient's 5-year-old sister, also developed the disease 1 year later. An HLA-nonidentical BMT resulted in unmaintained remission for 1 year, with autologous hematologic reconstitution followed by disease relapse. HLA-nonidentical BMT failed in three other patients with active disease at time of transplant. The poor long-term results of chemotherapy alone justify the use of related HLA-matched BMT in complete remission.