Introduction – The elimination of viral hepatitis and the prevention of HIV transmission are key objectives of global and national health strategies. The collection of blood drops on filter paper following finger-prick testing has demonstrated clinical value in improving the diagnosis of infectious diseases, particularly among certain vulnerable populations. Materials and Methods – Screening for viral hepatitis (B, D, and C) and HIV was evaluated in 26 medical-social facilities (centers for addiction care, support, and prevention – CSAPA –, and centers for reception and harm reduction support for drug users – Caarud) over a 6-year period (2018–2023), using blood collected on filter paper (DBS). Demographic (age, sex), epidemiological (risk factors), clinical (fibrosis score), and therapeutic (treatment initiation, virological cure rate) variables were collected. Results – A total of 588 subjects, predominantly men (81.0%) with a mean age of 44.4 years (standard deviation, SD=9.7), were screened for one or more viruses. Three hundred twenty-three (54.9%) reported one or more risk factors (drug use, unprotected sex). More than one-third of the individuals (33.5%) evaluated had significant fibrosis (≥F2), of whom 11.2% had cirrhosis. The positivity rates for HCV (active infection), HBV, and HIV were 16.3%, 1.8%, and 1.3%, respectively. Only one chronic HBs antigen (HBsAg) carrier was infected with HCV. Among the 96 patients newly diagnosed with HCV, 80 patients received treatment with direct-acting antivirals (DAAs). The proportion of patients achieving virological cure was 90.0%. For patients newly screened for HBV (n=4) or HIV (n=2), 4 initiated anti(retro)viral treatment. Conclusion – Screening for hepatitis viruses and HIV using dried blood spots in medical-social addiction treatment facilities is feasible and easily implementable without additional staff. The positivity rates for HCV (active infection), HBV, and HIV were significantly higher than the prevalence rates observed in the general population. Most of the newly diagnosed cases were able to receive therapeutic care.