Despite a rapid increase in immigration from low-income countries, studies on immigrants' mortality in Italy are scarce. We aimed to describe differences in all and cause-specific mortality among immigrants and Italians residing in Turin and Reggio Emilia (Northern Italy), two cities participating in the Italian Network of Longitudinal Metropolitan Studies (IN-LiMeS). We used individual data from the municipal population registers linked to the cause of death registers. All people aged 1-64 years residing between 2001 and 2010 were enrolled (open cohort) and followed up until 2013. The mortality of citizens from high migratory pressure countries (as a whole, and for each macro-area group) was compared with that of Italians; differences were estimated by Poisson regression adjusted by age and calendar year mortality rate ratios (MRRs), and by age-standardized mortality ratios for the analysis of cause-specific mortality. Compared with Italians, immigrants had lower overall mortality (MRR for men: 0.82, 95 % CI: 0.75-0.90; for women: 0.71, 95 % CI: 0.63-0.81). Sub-Saharan Africans experienced a significant higher mortality than Italians (MRR for men 1.29, 95 % CI: 1.03-1.61; for women: 1.70, 95 % CI: 1.22-2.36). Higher mortality for immigrants compared to Italians was observed for infectious diseases, congenital anomalies, some site-specific tumours and homicide mortality. Our study showed heterogeneity in mortality across the macro-areas of origin, and in particular Sub-Saharan Africans seemed to be a vulnerable population. The extension to other cohorts of IN-LiMeS will allow the health status of immigrants and vulnerable groups to be studied and monitored in more depth.