Opsoclonus and ocular flutter are rare but well-defined disorders of the saccadic system. Ocular flutter is a burst of back-to-back horizontal saccades without an intersaccadic interval. If these saccades occur in all directions, the involuntary eye movements are called opsoclonus. The most common aetiologies are paraneoplastic, postinfectious, toxic-metabolic and idiopathic. The underlying malignancy is usually neuronal crest tumors in children or lung, breast or gynaecologic cancer in adults. The appearance of these syndromes should prompt the search for an occult malignancy.