Objectives. To identify the type and extent of weapons being carried among young people in Scotland, and to determine the relation between use of illegal drugs and weapon carrying. Design. Questionnaire school survey. Setting. Independent schools in cental Scotland and schools in Lanarkshire and Perth and Kinross. Participants. 3121 students aged 11 to 16 in 20 schools. Main outcome measures. Self completion questionnaire reporting history of drug use and weapon carrying. Results. Overall, 34.1% of males and 8.6% of females reported having carried;I weapon (P < 0.0001), ranging from 29.2% of boys aged 11-13 (classcs S1 to S2) to 39.3% of boys aged 13-15 (S3 to S4). These values are higher than those in a recent survey of young people in England. Weapon carrying in Lanarkshire was 70% higher for males than in the rural area of Perth and Kinross. Both males and females who had taken drugs were more likely to carry weapons (63.5% of male drug users versus 20.5% of non-users and 22.8% of female drug users versus 3.7% of non-users; both P < 0.0001). The proportions of males carrying weapons who used none, one, two, three or four, or five or more illegal drugs were 21%, 52%, 68%, 74%, and 92% respectively. A similar trend was found among females. Conclusions. Better information is needed on the nature and extent of weapon carrying by young people in the United Kingdom, and better educational campaigns are needed warning of the dangers of carrying weapons.