Low‐frequency (10–60 Hz) electrical noise has been measured for the first time in carbon fibers while they were subjected to tensile stress. The measurements were performed at room temperature. In all the fibers, a minimum in the noise was observed with applied stress. Low‐modulus ex‐PAN (polyacrylonitrile) fibers showed three times the increase in noise at the highest stress compared to the higher modulus fiber. Measurements were also made on vapor grown carbon fibers (VGCFs) both as‐grown and annealed. The highly graphitized VGCF showed the smallest increase in the noise with stress among the fibers studied. Our noise results can be related to the microstructure of the fibers. The fiber microstructure becomes better aligned with applied stress. Therefore, the noise would be expected to decrease. Our results, however, indicate that stress dependent noise in these fibers is caused by a combination of parameters such as fibril alignment and electronic characteristics.