Preliminary data are presented here from a study of drug transitions in the UK. These support the contention that differences in route of administration are likely to be reflected in differing patterns of drug use, and associated with differing health risks for the individual drug user. Heroin 'chasers' were found to have robust and long-term patterns of heroin use and could not merely be considered as pre-injectors. They were also younger. No differences were found in the typical daily doses prior to entering treatment between chasers and injectors. Subjects who usually 'chased the dragon' but who would also inject were less likely to have shared injecting equipment in the past. Transitions between different routes of use were found in most directions. However, changes from 'chasing' to injection were most common. Year of initiation into heroin use was also related to initial route of use.