The Internet based addiction prevention project www.drugcom.de of the Federal Centre of Health Education (BZgA) offers information and anonymous counselling for adolescents and young adults. The Internet project is based on a secondary preventive approach. The objective is to prevent misuse and addiction of substances/drugs and to reduce negative effects of consumption (risk competence). The effects of the project are on different levels: Transfer of knowledge and change of attitude and behaviour. The process evaluation is based on quantitative data from online questionnaires on the website and on the log file analysis of users, use and acceptance. According to the different sections of www.drugcom.de that the user has been visiting, different indicators are raised, e.g. comprehensibility of text, satisfaction with counselling service, completeness of information etc. In 2004 the number of visits per day compared with the previous year has almost doubled to more than at an average of 1,000 per day. Consumers of legal and illegal drugs build the majority of drugcom users. Their average age is 20 years. 79% of those asked have consumed an illegal substance once in their life as a minimum, mostly cannabis. The knowledge tests and the self test concerning alcohol are used especially often. The results show that it is possible to reach the target group of drug consuming young people by an Internet based service. The Internet project www.drugcom.de as an online-service of addiction prevention has been established with success.