Denial and minimization in self-reports of cigarette smoking are probably common among youth and other groups where smoking is discouraged. Chemical measures may obtain more accurate measurement of smoking habits in those groups. One such measure, saliva thiocyanate (SCN), was evaluated in 1,419 eighth grade students. In that group, 54.9% of students admitted to regular smoking of > one pack/week had thiocyanates ≥ 100 μg/ml compared to 2.3% nonsmokers at those levels. Of students who smoked ≥ 10 cigarettes in the prior 24 hours, 66.7% were at or above 100 μg/ml. Elevated SCN in nonsmokers was uncommon. Saliva SCN is a safe, inexpensive, and acceptable prevalence measurement for cigarette smoking. It can be used in place of self-reports to document smoking of greater than one pack/week in populations of youth.