To present the results of treatment with sustained-release fampridine (4-AP-SR) in patients with downbeat nystagmus.Series of cases with downbeat nystagmus treated with 10 milligrams of 4-AP-SR every 12hours. The clinical improvement and the variation of the nystagmus before and after the treatment were evaluated, recording the score in the Dizziness Handicap Inventory, the velocity of the slow phase of the nystagmus and its frequency.Three patients were treated, none of whom reported significant subjective changes during the treatment. No significant differences were detected in the Dizziness Handicap Inventory score or in the studied videonystagmographic variables.This communication does not present positive results on the use of 4-AP-SR. The contradiction with previous studies may be caused by a small sample size, by the etiology of the cases or by the way in which the results were measured.