Resection of the direct efferent cochlear bundle in the guinea pig causes greater reduction in the cochlear microphonic potential than is caused by resection of the crossed efferent cochlear bundle. The findings of the present series of studies are thought to constitute physiological proof of the existence, in the guinea pig, of another component of direct efferent cochlear fibers, other than the direct olivo‐cochlear fibers, which arises in cells of the reticular formation of the medulla.