The present invention relates to monoclonal anti-human YKL-antibodies which are capable to modulate biological processes in which YKL-40 plays a prominent role, e.g. inhibit the growth and/or inducing apoptosis of cells, in particular cancer cells. The invention also relates to pharmaceutical compositions comprising said antibodies and uses said antibodies and/or pharmaceutical compositions for treatment of a disease wherein inhibition of cell growth, cell differentiation, remodelling of extracellular matrix, metastasis and/or induction of cell death due to apoptosis is a prerequisite for successful curing. An antibody of the invention is capable of inhibiting biological function of YKL-40 in the above mentioned processes by binding to a specific epitope on YKL-40.