A first-principle investigation using the recently developed M05-2X density functional and the 6-311++G(d, p) basis set was performed to understand the nature of interaction between C-60 and nucleic acid bases and the Watson-Crick base pairs. It was found that C-60 forms stacking complexes with nucleic acid bases and base pairs. It was revealed that the strength of interaction of nucleic acid bases with C-60 follows the order: G > C > A > T > U, while the GC base pair forms stronger complex than the AT base pair with C-60. (C) 2010 Elsevier B. V. All rights reserved.