To evaluate psychotropic drug use in undocumented migrants and natives in the same conditions of poverty. We studied drug dispensation by a nongovernmental organization during the year 2014. Drugs were identified according to the Anatomical Chemical Therapeutic classification and their quantity was measured in defined daily doses (DDD). We determined the percentage of patients taking at least one medicine with psychotropic activity in relation to the total number of patients receiving medicines of any class. We also calculated the individual DDD for psychoactive drugs. The percentage of natives receiving this type of medicine is significantly higher than that of undocumented migrants. Individual DDDs for each class of psychotropic drug are comparable in Italians and undocumented migrants and, among the latter, no difference was found in relation to ethnicity. Our findings describe for the first time the use of psychotropic medicines by undocumented migrants. On this basis, we hypothesize that poverty is more important than migration and ethnicity in generating the need for this type of pharmacological treatment. Both natives and undocumented migrants show poor adherence to treatment. This situation should be considered when programming health interventions in this field for the very poor and undocumented migrants.