The study hypotheses is that the introduction of dose escalated treosulfan, in substitution to busulfan or melphalan, will reduce toxicity after allogeneic transplantation while improving disease eradication in patients with lymphoid malignancies not eligible for standard transplantation.

Inclusion Criteria:

1. Age less than physiologic 68 years.

2. Patients with NHL and HL with an indication for allogeneic transplantation as follows:

   • Aggressive lymphoma and Hodgkin lymphoma; relapse after autologous transplants
   • Follicular lymphoma; failure of at least one prior regimen

3. Disease must be at chemo-sensitive or stable status to prior therapy before transplant.

4. Patients must have an HLA matched related or unrelated donor willing to donate either peripheral blood stem cells or bone marrow. Matching is based on high-resolution class I (HLA-A, -B, -C) and class II (HLA-DRB1, -DQB1) typing. The goal is to transplant > 3 x 106 CD34+ cells per kg body weight of the recipient

5. Patients must sign written informed consent

6. Adequate birth control in fertile patients

Exclusion Criteria:

1. Overt progressive disease prior to transplantation.
2. Bilirubin > 3.0 mg/dl, transaminases > 3 times upper normal limit
3. Creatinine > 2.0 mg/dl
4. ECOG-Performance status > 2
5. Uncontrolled infection
6. Pregnancy or lactation
7. Abnormal lung diffusion capacity (DLCO < 40% predicted)
8. Severe cardiovascular disease
9. CNS disease involvement
10. Pleural effusion or ascites > 1 liter
11. Known hypersensitivity to fludarabine or treosulfan
12. Psychiatric conditions/disease that impair the ability to give informed consent or to adequately co-operate