This study examines the relationship between heroin-assisted treatment versus methadone maintenance and the criminal activity of 1,015 individuals participating in a German model project. The main objective is to investigate how these treatments contribute to a decline of criminal behavior. The analyses are based upon self-reported criminal offence and police data on alleged criminals. Logistic regression is employed to explain the variance in the 12-month prevalence 1 year after program admission. The results clearly show a decline of criminal offences among participants receiving maintenance treatment; this decline was significantly greater in the heroin group with respect to property crimes and drug offences. The multivariate analysis reveals that the effects are due to a decrease of illegal drug use and absence from the drug scene.
