Ataxia with oculomotor apraxia is an autosomal recessive inherited disease characterized by childhood onset of progressive cerebellar ataxia, oculomotor apraxia, and progressive motor peripheral neuropathy. The mean age at onset is approximately 4.7 years, with oculomotor apraxia appearing a few years later. Diagnosis is based on molecular genetic analysis for mutations of the aprataxin (APTX) gene (chromosome 9p13.1; ataxia with oculomotor apraxia 1). Ataxia with oculomotor apraxia 2 is caused by an unknown gene mutation at locus 9q34. We describe two siblings, born to consanguineous parents, who had clinical features of cerebellar ataxia, tremor, dysarthria, oculomotor apraxia, and motor peripheral neuropathy. Brain magnetic resonance imaging showed cerebellar atrophy and mild brainstem atrophy. Electromyography showed signs of axonal neuropathy. The molecular genetic analysis demonstrated the APTX mutation W279X at locus 9p13.3 (ataxia with oculomotor apraxia 1 disease), and psychologic studies showed mild cognitive impairment. We suggest that mentation can be compromised in ataxia with oculomotor apraxia 1.