We retrospectively evaluated 73 chronic myeloid leukemia patients receiving first-line imatinib and compared patients with molecular warning response (WR) with patients with optimal response (OR) and failure regarding short- and long-term outcomes. The cumulative major molecular response (MMR) rates in patients with OR were significantly higher at any timepoint than those achieved by the WR group. Patients with WR at 3 months had significantly inferior failure-free survival (FFS) than optimal responders, but overall survival (OS) was similar. At 6 and 12 months, the WR and OR groups had similar FFS and OS. Twenty of 23 patients with WR at 12 months achieved MMR with imatinib.