Serum levels of YKL-40, MMP-2 and MMP-9 in 27 patients with locally advanced breast carcinoma received neoadjuvant chemotherapy were measured. All patients underwent neoadjuvant chemotherapy named as FAC protocol (5-Fluorouracil, Doxorubicin and Cyclophosphamide) with 21 days interval. There was 26,7% decrease in mean serum YKL-40 levels (from 146,4 mu g/ml to 107,3 mu g/ml) in clinically responsive group. This level was almost unchanged in non-responsive group (P > 0, 05). There was 42, 1% decrease in mean serum YKL-40 levels (from 173,1 mu g/ml to 98, 8 mu g/ml) in pathologically responsive group. This decrease was more dramatic in patients with complete pathological response (70, 2%). However, this level was slightly increased in non-responsive group. Changes in serum levels of MMP-2 and MMP-9 were not found to be associated with tumor response. Serum measurement of YKL-40 can be a helpful tool to predict pathological tumor response in breast cancer patients with neoadjuvant chemotherapy but not MMP-2 and MMP-9.