Since Koerber1described the first case of retraction nystagmus in 1903, almost 50 others have been documented.2Pathologic studies seem to indicate that the responsible lesion is located in the periaqueductal region of the midbrain and perhaps in tectum or pretectum. An electromyographic study of patients with this abnormality was undertaken to gain some information concerning the peripheral mechanism which might offer indirect evidence related to central pathways. Method and Patient Material The apparatus and experimental method have been described in a previous publication.3The following are abbreviated case histories of three patients with retraction and/or convergence nystagmus studied electromyographically. Case 1 A 26-year-old white man noted the onset of double vision, frontal headache, nausea, and vomiting in March, 1961. Ventriculograms in May of that year demonstrated a block of the aqueduct, and a Torkeldsen procedure was done. Shortly thereafter, the patient developed a staphylococcal meningitis which