In 2004 the statewide Justice Health Adolescent Health Directorate established an Addiction Medicine service in the NSW Juvenile Justice system. Previous research had indicated that young people in contact with this system had significant alcohol and other drug related problems and tended not to access services. For the past four years Addiction Medicine Clinics have operated in all nine Juvenile Justice Centres, across NSW, and in the NSW Youth Drug & Alcohol Court programme. A statewide telephone clinical advice service is also provided. Over the first four years, the service has reached 891 young people - 82% male. The majority of patients (83%) were aged from 14 to 17 years, when they first came in contact with the service - 2% were younger (10 to 13 years) and 14% were older (18 to 22 years). The most common ethnic backgrounds were Aboriginal Australian (46%) and Australian Non-Aboriginal (35%) young people. The majority of patients come from western Sydney and western NSW - 22% from Sydney South West Area Health Service; 19% from Sydney West Area Health Service; and 15% from the Greater West Area Health Service. The commonest diagnosis is cannabis dependence (78%), followed by alcohol (64%) and psychostimulant (45%) abuse. Nicotine dependence is a presenting problem in 44% of patients, usually because they are not allowed to smoke in custody. Nicotine replacement therapy has been prescribed to 23% of the service's patients and 14% have been treated for other drug withdrawal. Twenty-one percent report intravenous drug use. Twenty percent have opiate use disorders and only 6% have been on methadone or buprenorphine treatment. Only four patients have been on acamprosate and three on naltrexone for alcohol dependence. Young people who come in contact with the Juvenile Justice system are a special population requiring innovative drug and alcohol service provision.