Preventive mouth care is essential for the well-being of palliative care patients, though it is not performed enough outside units devoted to these patients. Our study aimed at gaining better knowledge about carers’ attitudes and knowledge regarding this basic type of care. A validated questionnaire was sent anonymously to nurses and nursing assistants working in the medical units of ten hospitals in Brittany. Of the 2,467 questionnaires sent, 54 % were validated for use. The number of years of experience had little influence on nursing staff’s answers. One in twenty did not think that preventive mouth care is part of his/her duties. This care was considered unpleasant, and difficult, by 11 % and 22 % of nurses, and 13.5 % and 20.5 % of nursing assistants, respectively. A lack of knowledge was openly expressed with regard to oral diseases and dental prostheses. More than one in four did not know the functions of the mouth, or could not identify a healthy mouth. These results show the scope for improvement as well as the priorities for action. They will be used as baseline for our future program assessment.