Fourteen cases of spinocerebellar degeneration were examined. While the patients attempted to keep their eyes in the primary position, horizontal eye movements were recorded for 1 min in total darkness by infrared reflection oculography. Instability of eye position in the dark was observed in 10 patients. The range of the eye position error was 3–6° in 6 patients, 6–10° in 3 patients and over 10° in 1 patient. These results indicate that the cerebellum plays an important role in extraretinal (nonvisual) eye position control.