  We compare non-locality of interactions between different scales in
hydrodynamic (HD) turbulence and magnetohydrodynamic (MHD) turbulence in a
strongly magnetized medium. We use 3-dimensional incompressible direct
numerical simulations to evaluate non-locality of interactions. Our results
show that non-locality in MHD turbulence is much more pronounced than that in
HD turbulence. Roughly speaking, non-local interactions count for more than
10\% of total interactions in our MHD simulation on a grid of $512^3$ points.
However, there is no evidence that non-local interactions are important in our
HD simulation with the same numerical resolution. We briefly discuss how
non-locality affects energy spectrum.
