This study explored common drug treatment utilization patterns in the first four types of treatments entered by injection drug users (IDUs) with multiple admissions. A Massachusetts longitudinal database with all entries to all licensed drug treatment programs was used. Treatment repeaters' admission patterns varied considerably. For the years 1997-2001, there were 2,500-3,000 IDUs new to the system each year who became treatment repeaters and who had more than 250 utilization patterns. Only approximately half of these repeaters followed the 10 most common utilization patterns. The most common pattern (for 30% of the population each year) was only entering detoxification two to four times; the only other common pattern (involving 4-8% of the population) was having entered methadone maintenance twice or having entered detoxification then methadone maintenance. Studies are needed to identify the extent to which the absence of a systematic pattern is caused by client, payment, or treatment setting and systems issues. A key implication is the need to develop policies that provide support for states to develop continuum-of-care models for their drug treatment systems.