Background: The aim of this study was to evaluate the prevalence of blood-borne chronic viral infections in immigrants in Italy, and identify factors associated. Methods: A prospective screening program was performed in seven clinical centers operating in Campania, Apulia and Calabria in southern Italy, to identify immigrants with HBV, HCV or HIV infections. Findings: Of 4·125 immigrants observed in the study period, 3·839 (93·0%) agreed to be screened: 381 (9·9%) resulted HBsAg, 136 (3·5%) anti-HCV, 62 (1·6%) anti-HIV-positive and 1·448 (37·7%) HBsAg-negative and anti-HBc positive. Ongoing or previous HBV infection was observed more frequently in males (p=0·02 and p<0·001, respectively), whereas HIV infection in females (p=0·01). Immigrants from western Africa showed a higher rate of HBsAg positivity (p<0·0001), of HBsAg negativity/anti-HBc positivity (p<0·0001) and anti-HIV positivity (p=0·004) compared with those from other geographical areas. At multivariate analysis, ongoing HBV infection was associated with male gender (OR:1·49, 95% CI: 1·04-2·14) and origin from western Africa (OR: 4·67, 95% CI: 1·70-12·80) and eastern Europe (OR 3·44, 95% CI: 1·17-10·08). HCV infection was independently associated with male sex (OR 1·84, 95% CI: 0·99-3·42); HIV infection was associated with an older age (OR 1·04, 95% CI: 1·01-1·06) and origin from western Africa (OR 4·09, 95% CI: 1·26-13·29), while male gender was a protective factor (OR 0·45, 95% CI: 0·24-0·85). Interpretation: The high prevalence of HBV, HCV and HIV infections in our large cohort of immigrants should constitute a warning to Italian Healthcare Authorities to develop adequate cost-effective screening policies. Funding Statement: This work was financially supported by Gilead for the study “Evaluation of an innovative model to eliminate HCV infection in a high-risk population of undocumented migrants and low income refugees” (EUDRACT: 2017-001024-21). Declaration of Interests: All the authors of the manuscript declare that they have no conflict of interest in connection with this paper. Ethics Approval Statement: The study was approved by the Ethics Committee of the Azienda Ospedaliera Universitaria of the University of Campania Luigi Vanvitelli (214/2012; 481/2018).