More than 70 cases of crossed dextral aphasia have been reported in the literature since the end of the XIXth century. If a genetic, environmental or even pathological factor--or lack of information about it--could be suspected to be responsible of a majority of these cases, 10 of them in which all these factors were eliminated still remain. A summary of the neurological, neuropsychological and neurolinguistic features of these 10 cases shows, among other things: 1. that nearly all of them present a (left) motor deficit associated with a quite large and deep right-hemispheric lesion; 2. that most of them also report the presence of one or the other of the neuropsychological signs usually seen in right hemisphere lesions in dextrals; 3. that if reduction and agrammatism are frequent aphasic signs, fluent jargon is also reported, more so in written than in oral expression. Some of the hypotheses put forward to explain crossed aphasia in dextrals are discussed in the light of these facts. It appears that none of these hypotheses can satisfactorily account for the occurrence of a right hemisphere aphasia in some dextrals.