Because the beginnings of smoking and the development of addiction are a paediatric problem, detailed perspective research is hampered by serious ethical problems which do not permit the participation of children and adolescents. Our findings assembled hitherto are therefore based on extrapolation of results of studies on adults though it is generally accepted that addiction of adolescents differs from that in adults. In our trial we focused retrospective attention on investigation of smoking "attempts " of adolescent students of Brno secondary schools and schools for apprentices. Examination by means of questionnaires we elaborated makes it possible to compare the circumstances of the first smoking attempts in groups of adolescents who later have a different smoking behaviour. A group of 52 students of Brno secondary schools and schools for apprentices who volunteered to participate and who obtained informed consent of their parents comprised 27 smokers and 25 non-smokers with a history of smoking attempts. The smokers and non-smokers differed in several substantial characteristics: the mean age of the first smoking attempts was in non-smokers by more than one year higher than insmokers (13.5 vs. 12.1 years). Significantlymore adolescent smokers tried to smoke before the age of 10 years, the frequency of initial attempts at the age of 11 to 14 years being equal in both groups. Immediately after the first smoking attempt the majority of non-smokers did not perceive any special changes of mood, while the majority of smokers perceived this deed with satisfaction "that they managed it" or had a feeling of freedom. The same number of students in both groups reported that they disliked the smell of cigarette smoke: an unpleasant reminiscence of the first attempt was reported by 68% non-smokers and 34% smokers. Significantly more subsequent smokers repeated the first attempt: 14% on the same day, 25.9 % on the next day, 7.4 % after several days. There are significant differences also in the frequency of replies to the questionwhether they will smoke after 5 years: 92 % non-smokers and 37 % smokers gave a negative reply. The majority of young smokers and non-smokers were careful during their first attempt: they did not smoke the whole cigarette and tried to avoid inhaling into the lungs. The differences between groups of later smokers and non-smokers were not statistically significant. Among everyday smokers the most numerous group is formed by children who smoke 6-10 cigarettes per day (47.4%), another 31.6% smoke 1-5 cigarettes per day. More than one fifth of the children (21.1%) reported that they smoke usually 11-20 cigarettes per day. Occasional smokers and those smoking 1-5 cigarettes smoke at special occasins; some 16% chidren reported that they smoke 20 cigarettes per day and the same number smokes 30 cigarettes or more. The majority of smoking children inhales the smoke into the lungs (always 74.1%, usually 14.8%). Themajority ofsmokers (77.8 %) prefers certain cigarettes brands,most frequently Petra (42.9 %), Lucky Strike (23.8 %), Marlboro and LM (19.0 %). One third of present smokers in the group are convinced that they can stop smoking at any time, more than 40% associate possible cessation of smoking with draval symptoms. Fromthequestionnaireaddressedtosmokersquestionswereselectedwhichcould be used for evaluation of the degree of addiction of adults. Ten questions were used where also specific conditions which in some children limit smoking were taken into cosideration. The intensity of smoking measured by the number of smoked cigarettes per day is evaluated on a wider scale than it is usually done in adults.

        Key words: smoking - smoking behaviour of secondary school students - pilot study - questionnaire for retrospective investigation of the smoking history