Using their own questionnaire comprising 10 items the authors evaluated the dependence of student volunteers from Brno secondary schools and schools for apprentices (age 15 to 17 years) and compared anamnestic data with specific (cotinine in urine) and non-specific (CO in expired air) biological tests of exposure to smoking. Of the 147 students examined 42 % were non-smokers, 25 % occasional smokers and almost 33 % daily smokers. Almost 10 % children smoked more than 10 cigarettes per day, more than 20 % children reported that they smoked 60 or more cigarettes per week. According to score of dependence, prepared in advance, representing the sum of points for each answer 59 % respondents (incl. all non-smokers) were included among independent ones. The second most frequent sub-group were those "severely dependent" (almost 17 % of the subjects), 3.4 % of the examined subjects were included in the very severely dependent sub-group. Highly significant correlations were found between evaluation of the degree of dependence according to anamnestic data and biological indicators of exposure (cotinine/creatinine in urine and CO in expired air): the values of correlation coefficients were 0.615 and 0.764. Both biological markers of exposure correlated significantly inversely with the time since the last exposure to active as well as passive smoking. Individual items of the questionnaire on dependence were significantly positively related to objective indicators of exposure. The closest correlation was found for the question relating to the first cigarette in the morning with the highest correlation coefficients, followed by signs evaluating the frequency of smoking and the usual number of cigarettes smoked per day and per week. The loosest relationships were found in signs testing at which occasions the young people smoke most frequently and whether they have any symptoms after enforced abstinence and what these symptoms are. The authors confirmed that regularly smoking children aged 15-17 years inhale the smoke and that they are internally exposed to nicotine. In this age group there are alreadymanyof thosewhoare severely or very severelydependentonnicotine. Therefore it is important to support "quit smoking " and treatment of nicotine dependence by indicated recommendations regarding preparations of nicotine substitution therapy.

        Key words: smoking - teenagers - dependence - test