The aim of this article was to present data about oral hygiene and knowledge about dental diseases and dental care habits in 10-15 year olds in Jönköping, Sweden and 10-11 year-olds in Da Nang, Vietnam in 2003. Methods A random sample of 206 individuals 10 and 15 year olds, from the City of Jönköping and 369 individuals from the City of Da Nang, were asked about their attitudes towards and knowledge of teeth and dental care habits. Results In Jönköping 9% answered that gingivitis is the same as inflammation of the gum. In Da Nang study 40% knew about early sign of gingivitis (easily gum bleeding).  67% in Jönköping answered that bacteria and sugar cause the acid that gives caries. In Da Nang 47% could answer correctly the cause of dental caries. The percentage of children who brush their teeth twice a day was the same, around 80 %, in both studies. In Jönköping 100% of the children used fluoride toothpaste. In Da Nang 73 % always used Fluoride toothpaste and 14 % did not know if the toothpaste they used contained Fluoride or not.