The problem of illicit drug use has been a long standing problem in Malaysia. It is well recognized that drug mis-use is associated with many social, economic and health problems, including mental health problems. Anxiety disorders have consistently been cited as the commonest type of psychiatric disorder in drug users. In Malaysia, many drug users are incarcerated in rehabilitation centres and prison. They form a different type of population as compared to the drug user in the general population, due to the effects of incarceration. With this in mind, a study was carried out in a rehabilitation centre, looking at anxiety disorders. Utilizing the SCID, we found current and lifetime diagnoses for anxiety disorders at 63.4% and 67.6% respectively. Suggestions are made in regards to our findings.