Background: Using direct-acting antivirals (DAAs) for recently acquired hepatitis C virus (RAHCV) infections, particularly in human immunodeficiency virus (HIV)-positive men who have sex with men (MSM), dramatically reduced the incidence of hepatitis C. However, implementation into clinical practice is challenging. The aim of this study was to analyze spontaneous clearance (SC) rates of RAHCV and to identify predictors of SC., Methods: The PROBE-C study is an observational European cohort on RAHCV infections in HIV-positive MSM. Between 2007 and 2017, RAHCV infections were documented with ≥12 months of follow-up. Fisher exact, χ2, and Mann-Whitney U tests were used for statistical analysis., Results: A total of 464 RAHCV infections were documented; 457 of 464 patients (98%) were male, and the median age (interquartile range [IQR]) was 41 (38-46) years. The main risk group for hepatitis C virus (HCV) transmission was MSM (98.9%). Most participants were infected with HCV genotype 1 (78.3%). The median baseline HCV RNA level (IQR) was 230 000 (135 000-474 432) IU/mL, and the median CD4+ T-cell count was 574/µL (547-604/µL. Of all cases, 92% received combination antiretroviral therapy, with 91% showing suppressed HIV RNA levels (<200 copies/mL). The median maximum alanine aminotransferase level (IQR) was 445 (402-522) U/L. SC of RAHCV infection occurred in 55 of 464 cases (11.9%). A >2-log decline in HCV RNA levels 4 weeks after diagnosis of RAHCV infection was the strongest predictor of SC (P < .001; sensitivity, 96.4%; specificity, 97.5%; positive predictive value, 84.1%; negative predictive value, 99.5%)., Conclusions: SC of RAHCV in HIV-positive MSM is found in only 11.9% of cases and a <2-log drop in HCV RNA level at week 4 after diagnosis should prompt early DAA-based treatment. However, immediate DAA treatment for RAHCV infection may also be favored in patients with ongoing transmission risk behavior., Competing Interests: Potential conflicts of interest. M. B. M. reports payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Gilead and Virology Education and support for attending meetings and/or travel from Gilead. S. S. reports honoraria for lectures and/or consultancies from AbbVie, Gilead, Janssen, GSK, MSD, ViiV Healthcare, Theratechnologies, and INSTO (paid to the author); grants or contracts from Kassenarztlicher Vereinigung Northrhine (as a physician in the compulsory health system), AOK Rheinland-Hamburg (integrated hepatitis C care contract), Immuno Heiddelberg (Match 1 and Match 2 studies), ViiV (TANGO, SALSA, SOLAR, DOMINO, CARLOS, DYNAMIC, URBAN, and JUNGLE studies), Gilead (BICSTAR study), Robert-Koch-Institut (Serokonverter study), Deutsche Leberhilfe (Hepatitis C Register study), Technische Universitat Muchen (Swapti study), INSTO (VMQ), Kompetenznetz Pneumonie (CAPNETZ study), and Medizinische Hochschule Hannover (TOP-HIV study); payment for expert testimony from ViiV and Gilead; support for attending meetings and/or travel from Gilead, Janssen, and GSK; participation on a data safety monitoring board (DSMB) or advisory board for ViiV, Gilead, MSD, and Theratech (paid to the author); and unpaid service to Landeskommision AIDS Northrhinewestfalia (as a board member), Arbeitsgemeinschaft niedergelassener Ärzte in der Versorgung HIV-Infizierter Nordrhein e.V. (NÄAGNO) (as a member of the governing board), AIDS Hilfe Cologne (as a consultant), and Deutsche Arbeitsgemeinschaft niedergelassener Ärzte in der Versorgung HIV-Infizierter e. V. (dagnä e.V.). C. D. S. reports grants and personal fees from AbbVie, Janssen-Cilag, MSD, ViiV Healthcare (during the conduct of the study), BioNtech, and Eli Lilly; grants, fees, and nonfinancial support from Gilead Sciences; grants from Cepheid; personal fees from GSK, Eli Lilly, Formycon, Molecular Partners, Roche, and SOBI; fees from AstraZeneca; other support from Apeiron; grants, personal fees and nonfinancial support from BBraun Melsungen; and grants or contracts from Pfizer and Synairgen. T. R. reports grants, consulting fees, speaking honoraria, and advisory board fees from AbbVie, Gilead, and MSD and support for attending meetings and/or travel from AbbVie and Gilead. S. M. has received honoraria for lectures and/or consultancies from AdBoard, Gilead, Janssen, MSD, ViiV, and Gilead. J. K. R. has received honoraria for lectures and/or consultancies from CCO, Medscape, Virology Education, Abivax, Galapagos, Gilead, Merck, Janssen, Theratechnologies, and ViiV and has participated on a DSMB or advisory board for Abivax and Galapagos. C. B. has received honoraria for lectures and/or consultancies; support for attending meetings and/or travel from AbbVie, Gilead, Janssen, MSD, and ViiV; and funding from Dt Leberstiftung, German Centre for Infection Research (DZIF), Hector Stiftung, and the NEAT ID Foundation. C. B. has also participated on a DSMB or advisory board for the MAVMET study (unpaid participation) and serves on the European AIDS Clinical Society governing board and as scientific secretary for DAIG. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. 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