The number of prisoners in Sweden categorized as drug abusers have increased substantially in the last 20 years according to the Swedish Prison and Probation Service (SPPS). Drug abusers are defined by SPPS as those who have used illicit drugs during the previous 12 months (Ekbom et al. 2006). In 1970 about 20 % of the prisoners could be classified as drug abusers, while they made up 28 % of the prison population in 1997 (Amilon and Edstedt 1998). In 2010 the number of prisoners with drug problems had risen to 60 % (Ekbom et al. 2011). One reason for this increase may be the sentencing policy.