BackgroundTheInner Santiago Health Study(ISHS) aimed to (i) estimate the prevalence of common mental disorders (CMD; i.e. depressive and anxiety disorders) among immigrants of Peruvian origin in Chile; (ii) determine whether such immigrants are at higher risk of CMD when compared with the native-born geographically matched population (i.e. non-immigrants); and (iii) identify factors associated with higher risk ofany CMDamong this immigrant group. A secondary aim was to describe access to mental health services by Peruvian immigrants meeting criteria forany CMD.MethodsFindings are based on a population-based cross-sectional household mental health survey of 608 immigrant and 656 non-immigrant adults (18-64 years) residing in Santiago de Chile. Diagnoses of ICD-10 depressive and anxiety disorders and ofany CMDwere obtained using the Revised Clinical Interview Schedule. The relationships between demographic, economic, psychosocial, and migration-specific predictor variables, and risk ofany CMDwere analyzed with a series of stepwise multivariate logistic regression models.ResultsThe one-week prevalence ofany CMDwas 29.1% (95% CI: 25.2-33.1) among immigrants and 34.7% (95% CI: 30.7-38.7) among non-immigrants. Depending on the statistical model used in the pooled sample, we found the prevalence ofany CMDamong non-immigrants to be higher (OR=1.53; 95% CI: 1.05-2.25) or similar (OR=1.34; 95% CI: 0.94-19.2) when compared with immigrants. In the multivariate stepwise regression ofany CMDin immigrants only, the prevalence was higher for females, those with primary compared to higher education, in debt and exposed to discrimination. Conversely, higher levels of functional social support, sense of comprehensibility, and manageability were associated with a lower risk ofany CMDin immigrants. In addition, no differences were observed between immigrants and non-immigrants reportingany CMDin mental health service utilization.ConclusionOur results evidence high levels of current CMD in this immigrant group, particularly amongst women. However, lower adjusted prevalence ofany CMDin immigrants compared to non-immigrants was limited to preliminary statistical models, thus failing to provide clear support for a “healthy immigrant effect”. The study sheds new light on differences in CMD prevalence by immigrant status in Latin America by examining differential exposure to risk factors in immigrant versus non-immigrant groups.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-023-15793-7.