Blood tests are recommended 2 times per year. Your doctor will discuss with you how often you should have blood tests. Bone marrow will be done if your doctor thinks it is necessary to check your disease. You must return to MD Anderson at least once every year. You may not need a bone marrow test every visit, but you will have blood drawn to measure the amount of disease you have. If the leukemia cannot be found for 2 years or longer on the blood test called PCR which is done to measure the amount of disease you have, your doctor may talk to you about stopping treatment with imatinib. If you and your doctor decide to stop your therapy, you will have a blood test for PCR done every 3 to 6 months. You do not need to return to MD Anderson to have this blood test done. You may have the blood taken by your local doctor and mailed to MD Anderson. If the leukemia is found again by the PCR blood test, your doctor may recommend that you restart treatment with imatinib. You may decide to stay on treatment with imatinib even if your PCR blood test does not show any sign of leukemia for 2 years or longer.