The electronic structure and properties of the armchair boron nitride nanotubes (BNNTs) interacted with the 5-FU drug, as an anticancer drug, are studied at the B3LYP/6-31G(d,p) level of theory. D3-Corrections were carried out for the treatment of intermolecular interactions in the hybrid complexes and encapsulated nanotubes, exactly. Results have shown that the encapsulation and adsorption of 5-FU molecule on the studied BNNTs surface are favorable processes, with a few exceptions. Also, it is found that the encapsulated nanotubes are stable than the hybrid complexes. Furthermore, we estimated the strengths of the intermolecular bonds of the benchmark systems by energetic, geometric, topological and molecular orbital descriptors. Some analyses have been made to explore any changes in the binding characteristics of the drug molecule after its attachment to the nanotubes. According to the NBO results, the charge transfer phenomenon is observed from the bonding or nonbonding orbitals of drug to the antibonding orbitals of BNNTs. Moreover, HOMO-LUMO analysis indicated that, after the adsorption process, the HOMO value slightly increased, while the LUMO value in these systems significantly reduced in the both of Drug@BNNTs groups. So, the energy gaps between HOMO and LUMO (Eg) are reduced, which emphasis on the greater intermolecular bond strength. Finally, the stability and reactivity of the Drug@BNNTs complexes have been examined from the magnitudes of the chemical reactivity descriptors such as chemical potential, global hardness, and electrophilicity index. As a consequence, BNNTs can be considered as a drug delivery vehicle for the transportation of 5-FU as anticancer drug within the biological systems. (C) 2017 Elsevier B.V. All rights reserved.