The authors describe a case of Kleine-Levin syndrome (KLS) which in the hypersomniac period presents, together with the classical symptoms, frequent arousals accompanied by sleep terrors. Polygraphic study shows the absence of any nyctohemeral cycle and very frequent parasomnias occurring during arousals from NREM sleep. On the basis of data from the literature, the authors suggest that a disturbance of maintenance of sleep might not be exceptional in KLS, even if none of the previous reports describes such frequent parasomnias.