BMT can cure several congenital immunological defects: if in these disease the engrafting is easier, the GVH reactions are more frequent and severe. The possibility to deplete from T lymphocyte the marrow before infusion, has overcame this difficulty. From 1968 183 BMT have been performed in Europe on patients with SCID (70 from HLA-identical donor, 113 from HLA-nonidentical donor). The survival after 2 years is 76% in the first group, and 56% in the second group (100 marrows have been T-depleted with different techniques). Strict isolation procedures before the transplant are very important to achieve good results. The possibility to treat different immunodeficiency With BMT are also discussed.