Six patients with a distinct syndrome of persistent sensations of imbalance are presented. Common features included onset following a period of motion exposure, symptoms lasting months to years, mild unsteadiness and anxiety, minimal relief from antivertiginous medication, and normal neurologic and quantitative vestibulo-ocular examinations. One patient experienced recurrent episodes. Mal de debarquement refers to sensations of motion experienced on return to stable land after adaptation to motion lasting from hours to days in normal individuals. The presented patients exemplify a syndrome of persistent mal de debarquement. The entity is found in a relatively small number of dizzy patients. Persistent mal de debarquement is discussed in the context of what is known about long-term vestibulo-ocular adaptation to alterations of visual or vestibular environments.