Peak velocities of visually elicited saccades and latencies of saccades have been studied in a patient with a large tumor in the pineal gland are that exerted compression in the direction of the corpora quadrigemina and underlying structures. Clinically it effected, among other symptoms, a severely impaired vertical upward gaze. Four repeated examinations were performed from initial radiation therapy to 12 months post therapy; normal data were derived from ten control subjects. Following therapeutic intervention, upward and downward gaze normalized almost completely, but peak saccade velocities in vertical directions remained markedly reduced, although there was a slight improvement in upward direction only. To examine whether the patient could generate short latency ‘express’ saccades, latencies of horizontal and vertical eye movements were also measured with a ‘gap-paradigm’ which included a 200 ms gap between peripheral target onset and fixation point offset. Surprisingly, the amount of ‘express’ saccades was significantly reduced only in the vertical plane. After one year post-treatment a slight decrease in saccade latencies was found in downward direction.