Despite concern on the impact of coronavirus disease 2019 (COVID-19) pandemic on undocumented immigrants, quantitative evidence on the issue is scant. We analyze socioeconomic and health conditions of 1590 undocumented immigrants in Milan, Lombardy, one of the regions with the highest COVID-19 clinical burden in the world that does not guarantee access to primary care for these individuals. We document a sharp reduction in visit number after lockdown, with 16% frequency of acute respiratory infections, compatible with COVID-19. Moreover, housing conditions make it difficult to implement public health measures. Results suggest the need to foster primary care by undocumented immigrants to face COVID-19 emergency. © 2020 The Author(s). Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.