It is shown experimentally, for the first time, that the drive current noise could lead to an important increase of the linewidth and a Gaussian line shape of tunable multielectrode DBR lasers. As an example, the drive current noise induced linewidth (DCNIL) has been measured to be about 120 MHz using a standard dc source through a 50 OMEGA resistor to drive the Bragg section of a tested DBR laser. For tunable lasers with a electronic tuning efficiency of more than 1 GHz/mA ultralow noise current sources should be used to ensure a negligible DCNIL.