Effects of tube inclination angle on nucleate pool boiling heat transfer of water at atmospheric pressure have been obtained experimentally. Experiments were performed for seven angles (0 deg, 15 deg, 30 deg, 45 deg, 60 deg, 75 deg, and 90 deg) with a tube of 540 mm in length. It is found that the nucleate boiling heat transfer on the outside of a tube is strongly dependent on the tube angle of inclination. The maximum and minimum heat transfer coefficients occur at 30 deg and 75 deg, respectively. The major reason for the enhanced heat transfer is thought to be the increase in liquid agitation on the tube surface.