Defect centers in optical fibers induced by drawing were investigated using the electron spin resonance technique. The hydrogen hyperfine (hf) doublet with splitting of 119 G was observed for both GeO2‐doped and pure silica optical fibers, which contain few hydroxyl ions. The hf peak intensity was directly proportional to specific surface area of optical fibers. These results indicate that the hf doublet arises from the hydrogen interaction with a drawing‐induced germanium defect center at or near the optical fiber surface.