To calculate the prevalence of mental disorders (anxiety, depression and psychosis) in the immigrant population compared to autochtonous population in primary care, exploring the predictive value of socioeconomic and demographic factors in the outcome.

In a cross-sectional, prevalence study, a sample of 200 immigrants and 200 autochtonous individuals attending primary care were evaluated with the Mini International Neuropsychiatric Inventory, the Goldberg Anxiety and Depression Scale, the General Health Questionnaire, and a demographic information sheet.

Immigrants showed higher levels of psychopathology relative to autochtonous patients for most mental disorders. Socioeconomic and demographic factors, particularly those related to the immigrant's living and work condition were positively correlated with psychopathology. Rates of some mental disorders in the immigrant group exceed the expected levels to the extent that the findings may be spurious.

Immigrants are at greater risk for developing a mental disorder, however this would in part appear to be a result of socioeconomic and demographic factors. It may be the case that the elevated rates of immigrant psychopathology may in part be a function of error due to the lack of cultural equivalence of the instruments employed. Further study is required to clarify these points.