BACKGROUND: The United States Centers for Disease Control and Prevention promote HIV testing every 6 months among young men who have sex with men (YMSM) to facilitate entry into the HIV prevention and care continuum. Willingness to be tested may be influenced by testing services' quality. Using a novel mystery shopper methodology, we assessed YMSM's testing experiences in 3 cities and recommend service delivery improvements. METHODS: We assessed YMSM's experiences at HIV testing sites in Philadelphia (n = 30), Atlanta (n = 17), and Houston (n = 19). YMSM (18-24) were trained as mystery shoppers and each site was visited twice. After each visit, shoppers completed a quality assurance survey to evaluate their experience. Data were pooled across sites, normed as percentages, and compared across cities. RESULTS: Across cites, visits averaged 30 minutes (SD = 25.5) and were perceived as welcoming and friendly (70.9%). YMSM perceived most sites respected their privacy and confidentiality (84.3%). YMSM noted deficiencies in providers' competencies with sexual minorities (63.4%) and comfort during the visit (65.7%). Sites underperformed on Lesbian, Gay, Bisexual, Transgender visibility (49.6%) and medical forms inclusivity (57.95%). Sites on average did not discuss YMSM's relationship context (49.8%) nor provide risk reduction counseling (56.8%) or safer sex education (24.3%). Sites delivered pre-exposure prophylaxis information and counseling inconsistently (58.8%). CONCLUSIONS: Testing sites' variable performance underscores the importance of improving HIV testing services for YMSM. Strategies are recommended for testing sites to promote cultural sensitivity: funding staff trainings, creating systems to assess adherence to testing guidelines and best practices, and implementing new service delivery models.