We present new ( 3+1 ) dimensional numerical relativity simulations of the binary neutron star ( BNS ) mergers that take into account the NS spins . We consider different spin configurations , aligned or antialigned to the orbital angular momentum , for equal and unequal mass BNS and for two equations of state . All the simulations employ quasiequilibrium circular initial data in the constant rotational velocity approach , i.e . they are consistent with Einstein equations and in hydrodynamical equilibrium . We study the NS rotation effect on the energetics , the gravitational waves ( GWs ) and on the possible electromagnetic ( EM ) emission associated to dynamical mass ejecta . For dimensionless spin magnitudes of \chi \sim 0.1 we find that spin-orbit interactions and also spin-induced–quadrupole deformations affect the late-inspiral–merger dynamics . The latter is , however , dominated by finite-size effects . Spin ( tidal ) effects contribute to GW phase differences up to \sim 5 ( 20 ) radians accumulated during the last eight orbits to merger . Similarly , after merger the collapse time of the remnant and the GW spectrogram are affected by the NSs rotation . Spin effects in dynamical ejecta are clearly observed in unequal mass systems in which mass ejection originates from the tidal tail of the companion . Consequently kilonovae and other EM counterparts are affected by spins . We find that spin aligned to the orbital angular momentum leads to brighter EM counterparts than antialigned spin with luminosities up to a factor of two higher .