The solid state structure of 1-((1H-benzotriazol-1-yl)methyl)naphthalen-2-ol, C17H13N3O, shows that this Mannich base crystallizes forming intermolecular N···HO hydrogen bonds, rather than intramolecular ones. Factors contributing to this choice of hydrogen-bonding mode are discussed. The compound crystallizes in the monoclinic system, P21/c space group, with lattice constants: a = 11.7934(9) Å, b = 14.3002(14) Å, c = 8.4444(8) Å, β = 106.243(5) deg, V = 1367.3(2) Å3, Z = 4, F(000) = 576, R1 = 6.96%, wR2 = 11.4%.