• Fourteen patients with aberrant regeneration of the third cranial nerve were examined using self-developing photographs, motion pictures, and pupillography. These pupillary phenomena were noted: (1) sector contractions of the iris sphincter in response to light, (2) sector contractions of the iris sphincter associated with eye movements, and (3) an abnormal pupillary unrest. The observations strongly support the concept that after injury, fibers regenerate and sprout collateral branches that finally reach muscles of the oculomotor group other than those originally innervated.