General questions about the pellagra are discussed specially from the clinical and etiopathogenic standpoint; the classical forms of cutaneous., digestive and nervous disorders, which are clearer during the periods of greater insolations are described. Notwithstanding the necessity of keeping in mind those classical aspects of the illness, we must not, as the A. stresses, forget the milder cases, oligo-symptomatic or larvated forms. Referring to those cases, the A. believes to be necessary to call attention to the "pellagra sine pellagra", presenting no skin manifestations. The A. tries to show the frequency of the neurological and psychiatric aspects of the condition, stating that those aspects are certainly more frequent than the descriptions of he workers on the field suggest. This apparent little frequency being due either to inaccurate observation of the slight mental and neurological disorders, or to the non-consideration of the "pellagra sine pellagra", the diagnosis being settled only when cutaneous manifestations are evident. Documenting the statement, the A. reminds several observations of his own and of other Brasilian authors, not only those registered specially from the neurological standpoint, but also some others where this particular aspect was overlooked, even though very characteristic neuropsychiatric phenomena could be detected from the reading of the observations. The four cases repported were studied at the Neurological Clinic of the Hospital Getúlio Vargas. Two of them were characterized by the myelopathic form; one by a neuro-myelosis syndrome and the last by a complex picture, not only disorders of the chord and cerebellum being evident but also presenting confusion and dementia. The hysto-rathological study of the last case revealled fatty degeneration of the liver and changes in the neuvous system consisting of sclerosis folow-ing degenerative processes of the dorsal funiculi of the chord and of the posterior nerve roots, atrophy of the peripheral portions of the lateral funiculi, acute degenerative process of the neuvous cells of the cerebral cortex, cerebellum and chord, and slight cerebellar atrophy. Those neu-i opathological changes explain completely the nervous and mental disorders observed