Mal de débarquement syndrome (MdDS) is typified by a prolonged rocking sensation – for a month or longer – that begins immediately following a lengthy exposure to motion. The provoking motion is usually a sea voyage. About 80% of MdDS sufferers are women, and most of them are middle-aged. MdDS patients are troubled by more migraine headaches than controls. Unlike dizziness caused by vestibular disorders or motion sickness, the symptoms of MdDS usually improve with re-exposure to motion. The long duration of symptoms – a month or more – distinguishes MdDS from land-sickness. Treatment of MdDS with common vestibular suppressants is nearly always ineffective. Benzodiazepines can be helpful, but their usefulness is limited by the potential for addiction. Studies are ongoing regarding treatment with visual habituation and transcranial magnetic stimulation.