Sponsor's decision to halt the study.

This study is to evaluate efficacy and safety of Imatinib in two groups of patients; all patients should be diagnosed less than 3 months as chronic myeloid leukemia in a chronic phase. The group A, the reference group, will have 10% or less than 10% of the BCR-ABL level after three month dosing and be maintained their dose of 400mg/day. On the other hand, the group B, will have more than 10% and the dose will be increased from 400mg/day to 600mg/day. The superiority of the group B will be proved by evaluating the MMR rate of these two groups after 12 months of administeration of Imatinib.

Inclusion Criteria:

• at the age of 18 or more
• newly diagnosed within three months as a Chronic Myeloid Leukemia
• with positive Philadelphia chromosome and appearance of BCR-ABL transcript
• with 0 - 2 of ECOG Performance Status
• with normal renal function
• with normal hepatic function
• able to understand and decide to involve the study

Exclusion Criteria:

• history of radiation therapy for more than 25% of bone marrow due to other malignant diseases
• history of other clinically relevant malignant tumors
• with bleeding disorders which are not related to leukemia
• evidence of clinically relevant cardiac dysfunction
• with severe disease which cannot be regulated by other organs
• a previous administration of Imatinib more than a week prior to the first dose.
• participation in other drug study(eg. intervention trial) within 30 days prior to the screening visit
• HIV-infected
• females with pregnancy, childbearing or lactating potential
• other reasons determined by investigators