We report in this paper the measurement results of the relative intensity noise (RIN) in GaAs-AlGaAs laser arrays and the comparison with that of single stripe lasers. The results are in agreement with the noise theory based on the rate equation. The experimental measurements include relative intensity noise versus drive current, modulation frequency and temperature. And in these circumstances the theoretical prediction that the maximum of the relative intensity noise occurs when the lasers run exactly at their threshold current level is examined.