Tuberculosis (TB) is an infectious disease that declined significantly throughout the 20th century. Large-scale TB screening of entire populations in France and Germany has thus been replaced by active screening of risk-groups, particularly migrants. The article engages with its problems and practices on three levels: by looking at the way information on migrants as an at-risk group is produced through disease surveillance data; by analysing how such at-risk group data influence local screening practices; and by showing which political and medical problems arise in the field. I overturn the discussion about screening and surveillance of migrants as a risk-group by showing that it is not the stigmatisation of migrants through disease risk that is most at stake, but the invisibility of the most vulnerable among them in disease surveillance data and the way restrictive national immigration policies interfere with and subvert local screening and treatment practices targeting them. The aim of my article is to promote a pragmatic sociology of screening, while paying attention to the practical complexities, political conditions and medical ambivalences of screening and follow-up care, especially when the migrant groups concerned are socially, politically and medically vulnerable.