Both human and animal models indicate that perinatal methadone exposure produces a variety of short- and long-term neurobehavioral consequences, including disruption of normal development of striatal cholinergic neurons. Despite this, methadone maintenance is a standard method of managing pregnant heroin addicts, and the opioid receptor partial agonist buprenorphine is under evaluation for the same use. We now report that perinatal administration of either methadone or buprenorphine reduces the content of the neurotrophic factor nerve growth factor (NGF) in rat striatum, which may explain the behavioral deficits observed. Furthermore, although NGF content is reduced, there are no corresponding reductions in striatal NGF mRNA.