Abstract : Therapeutic adhesion is essential because it modulates the efficiency of treatment, the occurrence of side effects and the socioeconomic costs possibly associated with it. In haematology, in the particular case of Chronic Myeloid Leukemia, the «ADAGIAGI O» study performed by Noens and co-workers demonstrated that therapeutic observance is lower than the practitioners, the patients and the family members believe it is. This lack of adhesion can engender a decrease of the efficiency of treatment, in particular by imatinib. Factors such as the chronicity of the disease and the length of treatment modify therapeutic adhesion over time. Simple methods, addressing both the patient and the doctor should be developed to improve this therapeutic adhesion.