Andrea Antinori,1 Paola Meraviglia,2 Antonella d’Arminio Monforte,3,4 Antonella Castagna,5,6 Cristina Mussini,7 Teresa Bini,4 Nicola Gianotti,5 Stefano Rusconi,8 Elisa Colella,8 Giuseppe Airoldi,9 Daniela Mancusi,10 Roberta Termini10 1Clinical Department, National Institute for Infectious Diseases “L. Spallanzani”, Rome, 2Department of Infectious Disease, “L. Sacco” University Hospital, 3Department of Health Sciences – University of Milan, 4Clinic of Infectious Diseases, “San Paolo” Hospital, 5Infectious Diseases, San Raffaele Scientific Institute, 6Università Vita-Salute San Raffaele, Milan, 7Institute of Infectious Diseases, University of Modena and Reggio Emilia, Modena, 8Infectious Diseases Unit, DIBIC Luigi Sacco, University of Milan, 9Studio Associato Airoldi, Cicogna, Ghirri, 10Janssen-Cilag SpA, Medical Affairs, Cologno Monzese, Milan, Italy Abstract: Current antiretroviral (ARV) therapy for the treatment of human immunodeficiency virus (HIV-1)-infected patients provides long-term control of viral load (VL). Darunavir (DRV) is a nonpeptidomimetic protease inhibitor approved for use with a ritonavir booster (DRV/r). This study evaluated the effectiveness of DRV/r in combination with other ARV agents in routine clinical practice in Italy. In this descriptive observational study, data on utilization of DRV/r, under the conditions described in the marketing authorization, were collected from June 2009 to December 2012. Effectiveness (VL