Optokinetic after nystagums is affected by many factors. We investigated the changes of OKAN response after repeated optokinetic stimulation. Normal subjects(n=9) received optokinetic stimulation for 60 seconds(40deg/sec 5.16 target spacing) and then OKAN was recorded for 20 seconds. The subjects were exposured on optokinetic stimuli three times first day. Time intervals were 1, 2, 5, 7, 14, 21, 28, 42 and 49 days following the last test. Time constant, initial slow phase eye velocity(2sec) and numbers of OKAN were evaluated. Time constant and numbers of OKAN have decreased after first exposure of optokinetic stimuli and reduction of OKAN has been maximized after 3 performance of OKAN test. After 28 days following the last test, the OKAN response was recovered same as a degree of initial OKAN response. Asymmetry increased by repeated stimulation between 1 day and 7 day but there was no statistical difference. Maximum decrease of initial slow phase eye velocity was shown after 3 performance of OKAN test but recovery of OKAN response was slow without statistical difference. OKAN was decreased by repeated exposure on optokinetic visual stimuli. The effects of repeated stimulation was disappeared after test interval of 4 weeks or more.