A national, representative, school-based sample of Portuguese youths was used to examine the prevalence of alcohol use in this population and to analyse differences between demographic variables such as gender and age, as well as to propose a statistical procedure that optimally quantifies categorical variables. Data on 6109 state school students from Portugal, in the 6th, 8th and 10th grades, aged 11–18, who participated in the 2002 (Health Behaviour in School-aged Children/WHO) survey of adolescent health, were analysed. Adolescents aged between 11 and 14 were placed in the younger group, and those 15–18 years old were placed in the older group. Optimal scaling was used to optimize the computation of factor scores, which were subsequently submitted to multiple regression analysis in order to analyse the impact of gender and age on alcohol use. The results of this study show that the majority of Portuguese school-aged adolescents attending regular school at 6th, 8th and 10th grades do not drink alcoholic beverages (beer, wine or spirits) on a regular basis (at least once a month). However, about 8% of these adolescents do drink beer, 3% do drink wine and 12% do drink spirits on a regular basis.With regard to age and gender, about a quarter of the older boys stated that they drink beer or spirits regularly. The multiple regression analysis showed that age and gender had a significant impact on alcohol use. Alcohol – in particular spirits – is a substance used by some Portuguese adolescents. Alcohol use and abuse is more frequent in boys and increases with age. The importance of these findings for health promotion strategies is discussed.