Allogeneic transplants have been shown to be effective in patients who have refractory CLL, have relapsed quickly after having received optimal therapy, and or have certain mutations or deletions.

Drawbacks include its high toxicity and the requirement that patients who will be undergoing the therapy be under 65 and in good health. It is currently just a treatment option to be considered for young patients with no comorbidities and with 17p deletion or mutation in the p53 gene and with disease that is refractory to all other approved treatments.