Imatinib-induced macrocytic anemia was known to result from c-kit inhibition in chronic myeloid leukemia (CML). However, recent studies showed that the prevalence of anemia is increased with high trough imatinib level and increased doses of imatinib influence decreased proliferation of burst forming units-erythroids (BFU-Es). The aim of this study was to evaluate the continuously increased mean cell volume (MCV) level's correlation with cytogenetic response and the favorable outcome in early chronic phase (CP)-CML patients. Clinical importance of MCV level was evaluated to correlate with cytogenetic response and compared with Sokal score, a known excellent prognostic parameter of cytogenetic response (CCR) in 84 early CP-CML patients. The patients with early and continuously increased MCV level irrespective of anemia achieved higher CCR after 12 months of imatinib therapy than patients with non-CCR (p=0.011). When the value was compared with low Sokal score, elevated MCV was independent predictor of CCR (RR=12.925, p=0.002 vs. RR=35.445, p<0.001). Furthermore, the patients with early and continuously increased MCV level had a higher probability of maintaining CCR than non-increased level (p=0.019). Increased MCV level was surrogate marker of achievement and durability to CCR for early CP-CML patients in the present study.