The aim of this phase II trial is asses the tolerability and the effectiveness of imatinib in patients with chronic myelogenous leukemia in chronic phase who are in relapse after stem cell transplantation.

Patients will received Imatinib at a dose of 400mg daily. The tolerability of Imatinib given at a daily dose of 400mg will be assessed. The hematologic, cytogenetic and molecular responses will be evaluated at various check points.

Donor/recipient chimerism during Imatinib therapy will be assessed. Survival will be estimated.

Inclusion Criteria:

• CML Ph+ (assessed by cytogenetic or FISH)
• Age ≥ 18 year at inclusion
• PS grade 0 to 2 (ECOG)
• previous allogeneic stem cell transplantation
• molecular, cytogenetic or haematological relapse in chronic phase after transplantation
• Immune therapy for graft versus host disease stopped within 2 months from inclusion
• Adequate and organ function, defined as the following: total bilirubin <3x uln, sgpt <3x uln, creatinine <2x uln.
• informed consent sign up

Exclusion Criteria:

• Age less than 18 y
• accelerated or blastic phase
• previous therapy with imatinib
• active malignancy other than CML or non-melanoma cancer of the skin
• current treatment with another investigational agent