In the EU action plan on drugs (2000–04), the third strategy target is 'to increase substantially the number of successfully treated addicts'. No aggregated data exist at European level to directly measure the level of achievement of this objective. However, many evaluations have been carried out across Europe exploring if and what type of treatment works. Findings on successful treatment are presented in this Selected issue according to the type of treatment intervention: withdrawal treatment, drug-free treatment and medically assisted treatment. The success criteria vary between the different types of treatment and are also related to social reintegration and rehabilitation after treatment.