Are the barriers to good oral hygiene in nursing homes within the nurses or the patients?Objective: To explore nursing home patients' oral hygiene and their nurses' assessments of barriers to improvement. Background: In nursing homes, nurses are responsible for patients' oral hygiene. Materials and methods: This study assessed the oral hygiene of 358 patients in 11 Norwegian nursing homes. 494 nurses in the same nursing homes participated in a questionnaire study. Results: More than 40% of patients had unacceptable oral hygiene. 'More than 10 teeth' gave OR = 2, 1 (p = 0.013) and 'resist being helped' OR = 2.5 (p = 0.018) for unacceptable oral hygiene. Eighty percent of the nurses believed knowledge of oral health was important, and 9.1% often considered taking care of patients' teeth unpleasant. Half of the nurses reported lack of time to give regular oral care, and 97% experienced resistant behaviour in patients. Resistant behaviour often left oral care undone. Twenty-one percent of the nurses had considered making legal decisions about use of force or restraints to overcome resistance to teeth cleaning. Conclusion: Oral hygiene in the nursing homes needed to be improved. Resistant behaviour is a major barrier. To overcome this barrier nurses' education, organisational strategies to provide more time for oral care, and coping with resistant behaviour in patients are important factors.