Among the compounds formed by an element of the 13th group and nitrogen, boron nitride, also called white graphene, stands out for its high strength and thermal conductivity, transparency to visible light, antimicrobial properties, high resistance to oxidation, and biocompatibility. One-dimensional and two-dimensional boron nitride nanostructures, i.e. nanotubes and nanosheets, respectively, are expected to present innovative advanced characteristics not equal to those of bulk boron nitride, bringing new perspectives to numerous applications in nanoscale electronics and biomedicine. For the correct design of systems and devices consisting of boron nitride nanosheets and nanotubes, understanding the mechanical behaviour of these nanostructures is extremely important. Firstly, because the robustness and functioning of nanosystems and nanodevices based on boron nitride nanostructures are determined by the mechanical behaviour of their constituents and also because deformation can influence the optical, electric, and thermoelectric properties of boron nitride nanotubes and nanosheets. In this context, the current chapter is dedicated to the numerical evaluation of the elastic properties of boron nitride nanosheets and nanotubes, using the nanoscale continuum modelling (also called molecular structural mechanics) approach. With this aim, a three-dimensional finite element model was used to evaluate their elastic moduli.