Nystagmus, defined as an involuntary repetitive, rhythmic to-and-fro movement of the eyes initiated by a slow drift that shifts an image off the fovea, is discussed in detail. The steps to take in evaluating nystagmus are emphasized , including the importance of close observation with the patient supine, prone, and lying on either side Central vestibular nystagmus due to disease of the central nervous system is covered fully and case studies include patients with upbeat nystagmus and with acquired pendular nystagmus.. When a saccadic eye movement takes the eye away from fixation (saccadic intrusion), a variety of saccadic oscillations can occur, in particular multidirectional saccades without an intersaccadic interval, which is diagnostic of opsoclonus; ocular flutter; or the two oscillations combined. . Two paraneoplastic syndromes illustrate these disorders , a case of ocular flutter associated with paraneoplastic encephalitis and cancer of the lung, and an infant with opsoclonus as the herald syndrome of a neuroblastoma.