Despite significant advances in HIV treatment, transmission remains a public health concern. In 2022, there were 1.3 million new HIV infections worldwide and 1,888 new diagnoses in Italy, with sexual transmission being the predominant route. Many individuals are still diagnosed late, and a portion of people living with HIV are unaware of their status. Pre-Exposure Prophylaxis (PrEP) has emerged as an effective biomedical strategy to prevent new infections, especially when integrated into comprehensive prevention efforts. Study Objectives The primary objective of this observational study is to establish a large prospective cohort of individuals using PrEP in Italy. The study aims to assess PrEP's effectiveness, tolerability, adherence, and barriers to long-term use in a real-world setting. These data will be instrumental in guiding future strategic interventions to optimize PrEP management and move toward the goal of zero new HIV infections in Italy. Primary Objective * To assess the incidence of new HIV infections among PrEP users in Italy. Secondary Objectives * Incidence of other sexually transmitted infections (STIs); * Tolerability of PrEP; * Psychological and behavioral aspects related to PrEP use; * Adherence and persistence in care; * Use of therapies and prophylaxis for STIs during PrEP use. Study Design and Coordination This is a prospective observational study, promoted by Fondazione ICONA in collaboration with clinical centers and community-based organizations. The coordinating enrolling center is INMI L. Spallanzani IRCCS in Rome. Participating Centers: * 49 university and hospital-based centers across Italy; * 4 non-clinical checkpoints offering PrEP screening, prescription, and follow-up. Study Population Adults (≥18 years) who are HIV-negative, sexually active, and considered eligible for PrEP per national or international guidelines, including both new and current PrEP users. Inclusion Criteria * Age ≥18 years; * Negative HIV test at enrollment; * Willingness to initiate or continue PrEP; * Informed consent provided. Exclusion Criteria * HIV infection or strong suspicion of infection; * Contraindications to PrEP medications; Known allergy to PrEP components; Refusal to comply with study procedures.