Multi-dose drug dispensing (MDDD) was introduced in Denmark in 2001 in order to minimize medication errors. In May 2010 44.500 Danish citizens received MDDD. We report two cases where MDDD in the primary sector led to medication errors after hospitalisation, the reason partly being difficulties in getting information on MDDD on admission, lack of knowledge on handling MDDD in hospital and inadequate communication between the primary and the secondary sector. These problems has until now been underestimated.