[en] BACKGROUND: Donor lymphocyte infusion (DLI) is currently standard therapy for relapse of malignancies after allogeneic BMT. Several observations suggest that both normal and leukemic progenitor cells of host origin constitute effective target cells for donor-derived lymphocytes. To prevent relapse of sickle cell disease (SCD), a child with evidence of decreasing mixed chimerism received DLIs 8 months after allogeneic BMT for SCD. CASE REPORT: A 4-year-old child who was homozygous for SCD underwent a transplantation of bone marrow from his fully HLA-matched sister. Routine detection of sex chromosomes in bone marrow cells evidenced decreasing mixed chimerism, which heralded a probably imminent recurrence of the disease. The patient received two DLIs in graded incremental doses on Days 234 and 267. One month later, he developed grade 2 acute GVHD that responded well to corticosteroids and cyclosporine. RESULTS: DLI resulted in complete donor chimerism within 2 months of the second infusion. Now, 2 years after the second DLI, the patient is in excellent condition, with normal Hb and excellent growth and development. CONCLUSION: This is the first report of successful use of DLI in a patient with probable imminent SCD recurrence after allogeneic BMT. It shows that DLI can displace residual host HPCs in case of recurrence of nonmalignant disease after allogeneic BMT.