The use of a supervised drug consumption room (DCR) in a newly established low threshold facility in Geneva, Switzerland, in 2002 is analyzed. Two sources of routine data were used: data collected at the first visit by any new client (entry questionnaire) which included some personal details, and data collected on the substances injected at each visit to the DCR. A typology of injection profiles was constructed. Overall, the mean number of injections and days of visits per client over the year was low and cocaine was the main substance injected. However, an important heterogeneity in the use of the DCR was found and five types of clients identified: 1-day clients; standard clients; heroin-oriented clients; high cocaine consumption clients, and newcomers. Typology was associated with some characteristics at the first visit and the drug consumption pattern in the month preceding the first visit was in accordance with the subsequent use of the DCR. This heterogeneity in the use of the DCR highlights the diverse roles of the DCRs in harm reduction.