Objective: To describe the status of dental caries in a sample of Iranian adolescents aged 14 to 18 years in Qazvin, and to identify caries-related factors affecting this group. Study design: Qazvin was divided into three zones according to socio-economic status. The sampling procedure used was a stratified cluster sampling technique; incorporating 3 stratified zones, for each of which a cluster of school children were recruited from randomly selected high schools. The adolescents agreed to participate in the study and to complete a questionnaire. Dental caries status was assessed in terms of decayed teeth (DT), filled teeth (FT) and decayed, missing and filled teeth (DMFT). A multivariate regression analysis was used to determine statistically significant associations between DMFT and other variables. Results: The study sample comprised 380 adolescents, 188 (49.5%) being male. The mean age of the adolescents was 15.42 (SD= 1.1) years, and the mean DMFT was 2.61 (SD=1.89). Boys had significantly higher DMFT scores than girls (P<0.05). The multivariate regression analyses revealed a significant relation between high DMFT scores and such variables as increasing age, male gender, lower levels of parental education, higher family income, lower frequency of tooth brushing and dental flossing, having a history of no visits to the dentist, and bad perception of own oral health. Conclusions: The present study reveals that Iranian adolescents have a poor oral hygiene, as very few subjects brush and floss their teeth on a regular basis. Although the incidence of caries was found to be moderate, it was influenced by demographic factors such as age and gender in addition to socio-behavioral variables such as family income, the level of education attained by parents, the frequency of dental brushing and flossing, and both the frequency and type of visit to a dentist.