In a ten-year study of Machado-Joseph-Azorean disease (MJAD), three distinct syndromes emerged: ataxia syndrome (11 patients), ataxia-motor neuron-extrapyramidal syndrome (four), and ataxia-motor neuron-extrapyramidal syndrome (two). Three patients had such advanced disease that classification was not possible. These syndromes more accurately describe functional deficits than did previous classifications. Spread of neuronal degeneration from the cerebellar system to the motor neurons of the spinal cord and brain stem was found for the first time, to my knowledge, in five patients and to the motor neurons and the extrapyramidal system in two of 14 patients followed up. There is no dementia, and peripheral neuropathy is a late complication common to all syndromes. World presence of MJAD could have begun with Portuguese overseas expansion in 1415. Alternatively, the possibility of multiple spontaneous mutations must be considered. Genetic sameness depends on a specific genetic marker, which is not yet available. For accurate genetic counseling, a nonspecific biologic marker for this disease is sought, and electronystagmography changes may prove helpful. This is particularly important as this illness, like Huntington's disease, is usually not manifest until the child-bearing years or after.