A cross-sectional dental questionnaire census survey was conducted in classrooms of 17,280 students aged 13-18 years in Skaraborg County, Sweden. The overall response rate, based on school attendance on the test day, was 91% with no gender differences at the senior level, and 86% (boys 87%, girls 85%) at the upper secondary level. The aim was to examine gender differences in knowledge, attitude, behavior and perceived oral health. A retest study showed good agreement. Thirty-one percent of the girls and 21% of the boys flossed regularly. Eleven percent reported daily candy consumption, with no significant gender difference. Girls, however, more often than boys considered their own consumption to be too high. This gender difference in attitude was most pronounced among older daily consumers (odds ratio (OR) = 5.8 [3.7-9.2]). Oral health was regarded as important by a majority of the students (95%). Girls considered sound teeth to be more important than did boys, both among the younger (OR = 1.7 [1.4-2.1]) and the older (OR = 2.4 [1.9-3.1]) adolescents. It is concluded that most adolescents had a positive dental attitude and perceived their own oral health to be good. Poorer knowledge and behaviors concerning oral health were demonstrated. Gender differences existed in most issues. Girls scored more favorably on behavioral measures, showed more interest in oral health, and perceived their own oral health to be good to a higher degree than did boys.