The authors describe a 46-year-old man who suddenly developed a typical cyclic esotropia. The most unusual aspects of this case were the late onset of the condition and the unilateral high myopia associated with a severe amblyopia of the squinting eye. The 24-hour-periods of deviation were accompanied by a very disagreeable flicker in the esotropic eye. The onset of this extremely unusual disorder and rare form of esotropia usually occurs at 2 to 4 years of age. To the best of our knowledge only 2 cases of cyclic esotropia have been described in adults hitherto.