In the RESINA/HIV-HEP-MASTER project, the development of HIV resistance is monitored before the start of the first therapy and at each change of therapy. Currently, 37 HIV centres from NRW are participating in this project, which is run in cooperation with the RKI. For the past 10 years, the analysis of resistance has not only been limited to HIV, but has also been extended to hepatitis viruses (B, C). HBV and HCV are analysed in the HIV-HEP-MASTER and PEPSI projects (DZIF funding). The data from these cohorts were integrated into the EURESIST database and analysed together with partners in Germany, Italy, Sweden and Israel.