OBJECTIVE: The aim of this study was to investigate the effect of tongue scraping and inter-dental flossing on morning bad breath in periodontally healthy subjects. METHODS: A four-step blind, cross-over study was conducted in 19 volunteers, divided into four groups: Group I: tooth brushing; Group II: tooth brushing and inter-dental flossing; Group III: tooth brushing and tongue scraping; and Group IV: tooth brushing, inter-dental flossing and tongue scraping. The volunteers performed these oral hygiene procedures three times a day for 7 days. Seven-day wash-out intervals were observed. Morning mouth breath was assessed organoleptically and by volatile sulphur compound concentrations. RESULTS: The highest mean organoleptic and volatile sulphur compound measurement values were found in the treatment groups in which tongue scraping was not performed and there were statistical differences between the two groups (p < 0.05). In the organoleptic evaluation (p > 0.05), inter-dental flossing did not show any statistical improvement in the effect of tongue hygiene on morning bad breath, but it significantly reduced the concentration of volatile sulphur compounds (p < 0.05). CONCLUSION: The findings suggest that tongue scraping appears to be the most important hygienic procedure to reduce morning bad breath in periodontally healthy subjects.