BACKGROUND: Biological factors influencing individual response to drugs are being extensively studied in psychiatry. Strikingly, there are few studies addressing social and cultural differences in attitudes toward psychotropic medications. The objective of this study was to investigate ethno-culturally determined beliefs, expectations and attitudes toward medication among a sample of hospitalized psychiatric patients. METHODS: An ad hoc questionnaire was designed to assess patients' expectations, attitudes and prejudice toward medication. The study included 100 adult patients hospitalized in Geneva, Switzerland. RESULTS: Patients were in majority male (63%), originated from Switzerland (54%) and spoke the local language fluently (93%). They took on the average 3 different psychotropic drugs. Sixty-eight percent of patients expected side effects and 60% were ready to stop medication because of them. Thirty percent of patients expected negative personal changes with treatment and 34% thought that their mental disorder could have been treated without drugs. Thirty six percent of the sample used alternative or complementary medicines. 35% of immigrant patients believed that medication had different effects on them than on local patients. When compared with Swiss patients, they more often reported that significant others had an opinion about medication (p = 0.041) and more frequently valued information provided by other patients about treatment (p = 0.010). CONCLUSION: Patients' attitudes toward medication should be investigated in clinical practice, as specific expectations and prejudice exist. Targeted interventions, especially for immigrant patients, might improve adherence.