Background: Previous studies have confirmed the effects of water extract of Crocus sativus on the euphoric and behavioral properties of morphine in male and female mice.Objective: In the present study, the effects of alcohol extract of Crocus sativus stigma on the acquisition and expression of morphine-induced conditioned place preference (CPP) in male Wistar rats (250-300 g) were investigated.Material and Methods: This experimental study was conducted on the 84 male rats that were divided in 18 groups (n=6/group). In a pilot study, different doses of morphine (0.5, 1, 2.5, 5, 7.5 and 10 mg/kg) and the extract (10, 50 and 100 mg/kg) were injected to the animals for evaluation of the drugs ability to induction of place preference. In the second phase of the experiments, the extract of the C. sativus was administered during or after induction of morphine CPP. Then, CPP were tested in the animals. One-way Analysis of Variance (ANOVA) was preformed for statistical procedure. Results: Administration of morphine (0.5, 1, 5, 7.5 and 10 mg/kg), indcreased the time spend in the compartment paired with morphine (i.e. conditioned place preference-CPP). The increment was significant for the dose 7.5 and 10 mg/kg of morphine. Administration of the plant extract (10, 50 and 100 mg/kg) did not change the time spent in the drug-paired side by the animals. Injection of the same doses of the extract before morphine (10 mg/kg) administration caused a decrease in the time spent in drug-paired side in doses 50 and 100 mg/kg of the extract. In addition, injection of the plant extract in the test day to the animals in which reveived morphine (10 mg/kg) in the conditioning days decreased the expression of morphine CPP in the animals which was statisticaly significant for doses 50 and 100 mg/kg of the extract.Conclusion: It could be concluded that injection of the alcoholic extract of C sativus can inhibit the acquisition and expression of morphine-induced CPP in the rats.