Psychiatric diagnosis is a clinical activity subjected to more clinical determinants than many others. Based on a unique human encounter, it resorts to a variety of informational sources and interpretive mechanisms that reflect strong cultural biases. Each diagnostic system has mirrored the period of history in which it became established. This article examines the effect of culture on the two best-known diagnostic and classificatory systems: the DSM-IV and the ICD-10 Section V. It is important to minimize the ethnocentrism of disease categories in psychiatry and to highlight sources of possible cultural biases in the diagnostic interview and the diagnostic process in general, including assessment of comorbidity levels of stress, multiaxial impairment, everyday functioning, and management recommendations. Research on these issues and on diagnostic and measurement instruments must be pursued without sacrificing mainstream conventions.