Morphine is a drug that can lead to addiction because of its rewarding effects. The present study investigated the effects of a hydro-ethanolic extract of Echinophora platyloba L. (Apiaceae) on the rewarding effects of morphine. The rewarding effects of morphine and the plant extract were evaluated using a conditioned place preference (CPP) paradigm in mice. Additionally, the effects of administering the plant extract on the expression and acquisition of morphine CPP were investigated. Finally, the role of opioid receptors in the CPP of the plant extract was determined. Both morphine and the extract induced a significant CPP. Furthermore, naloxone could inhibit the CPP of the plant extract. The plant extract had no effect on the expression of morphine CPP, but it significantly inhibited the acquisition of morphine CPP. Consequently, the extract of E. platyloba L. has rewarding effects, which may be mediated through opioid receptors. The extract can also inhibit the acquisition of morphine CPP. Manuscript profile