Since their first introduction to the world, both heat pipe and nanofluid have caught the interest of many researchers. Heat pipe with its unique and exceptional capability in transferring heat passively and effectively, was studied intensively and developed extensively for many applications. While nanofluid with its higher thermal conductivity and some other upgraded properties compared to conventional fluid rose as appealing research subject especially on fluid and thermal research area. This study analyzes the utilization of CuO-water nanofluid on biomaterial wick heat pipe. Laboratory-developed CuO-water nanofluid was used as working fluid for vertically straight-shaped biomaterial wick heat pipe. From the experiment, it was shown that the application of CuO-water nanofluid reduced the heat pipe thermal resistance up to 83%. It was figured out that this enhancement is due to the combination of higher thermal conductivity and better wettability of the fluid. It was also found that the heat pipe with nanofluid did not show significant degradation though being inactivated for several weeks. However, it was figured out that unlike the application of low concentration nanofluid, application of high concentration nanofluid was insignificant in improving thermal performance of the heat pipe.