  In this paper, we consider the scattering problem for a class of $N$-coupled
systems of the cubic nonlinear Schr\"odinger equations in three space
dimensions. We prove the scattering of solutions that have a mass-energy
quantity less than that for the ground states. This result is previously
obtained by Duyckaerts-Holmer-Roudenko for the single cubic nonlinear
Schr\"odinger equation in three space dimensions. It turns out that the result
can be extended to a wide class of $N$-coupled systems.
