Multiple plasmacytomas with IgA paraproteinemia, a low grade lymphoid neoplasm of differentiated B cells rarely seen in the young, were encountered in a 10-year-old child. T cell-depleted allogeneic bone marrow transplantation (BMT) was performed because of progressive disease despite chemotherapy. Donor T cells were infused after transplantation in gradually increasing numbers to achieve a graft-versus-tumor effect. Complete eradication of all tumor masses was achieved following BMT with normalization of serum immunoglobulin levels. The patient remains in complete remission 4 years after BMT. Allogeneic BMT should be considered early in the course of low-grade lymphoid malignancy in the younger age group.