The present investigation uses electrooculogram to evaluate multiple system atrophy (MSA) and late onset cerebellar atrophies (LOCAs), both idiopathic (ILOCA) and late onset autosomal dominant cerebellar ataxia (ADCA). Forty cases were clinically examined using scales for cerebellar, pyramidal, parkinsonian, mental status and neuroimaging quantitative evaluations. The patients were classified into three groups: olivopontocerebellar atrophy (OPCA), striatonigral degeneration (SND), Shy-Drager syndrome (SDS), and LOCA. We have used direct current electro-oculography in order to establish their validity in making the diagnosis. Cerebellar signs were significantly correlated with impaired VOR-fix gain and OKN, abnormalities of saccades, and reduced smooth pursuit gain (p < 0.05). Pons atrophy was significantly correlated with impaired VOR-fix gain (p < 0.01), abnormalities of saccades (p < 0.01), and reduced smooth pursuit gain (p < 0.05). Cerebellar hemisphere atrophy was significantly correlated only with impaired VOR-fix gain (p < 0.05), and medulla oblongata atrophy only with abnormalities of saccades (p < 0.05). Gaze-evoked nystagmus was found in 42.8% of patients with OPCA, and only in 14.2% with SND, but was not found in LOCA patients (t test, p < 0.05). In patients with OPCA, the combination of gaze-evoked nystagmus, abnormalities of sinusoidal VOR and reduced OKN gain measurements was very frequent, while infrequent in both LOCA (Fisher's exact test, p < 0.05) and SND subjects (p < 0.01). SDS also showed abnormalities of the oculomotor system.