Based on the 12,300 persons estimated to have been living with diagnosed HIV in Switzerland in 2012 (Kohler, Schmidt et al. 2015), we calculated Geneva's share of this number (11.4% according to cumulative notification data) and added the yearly new HIV cases 2013-2017 (notifications to the Swiss Federal Office of Public Health, FOPH), resulting in a estimated total of 1710 persons living with diagnosed HIV in Geneva in 2017. The ECDC HIV modelling tool was used to calculate the 2017 undiagnosed fraction in Switzerland. To calculate the number of PLWH in Geneva we assumed that the undiagnosed fraction in Geneva is similar as in the rest of the country. We then applied data from the Swiss HIV Cohort Study (SHCS): proportions of Geneva SHCS particicipants on ART and - among those - Geneva SHCS participants with less than 50 HIV-RNA copies, assuming that the Geneva SHCS proportions are representative for all people living with diagnosed HIV in Geneva. To avoid pseudo-accuracy for these crude estimates, absolute numbers were rounded to the next 10