['Although steady-state methadone (SSM) treatment is mainly used for opioid addiction, some clinical studies indicate that it also reduces cocaine abuse in opioid-dependent individuals.', 'To present evidence suggesting that SSM may be useful in the treatment of cocaine addiction without pre-existing opioid dependence. We review studies in animals investigating the effects of SSM on behaviors motivated by cocaine and on cocaine-induced alterations of genes expression in the rat brain.'] Do animal studies trigger new insights on the use of methadone maintenance?