BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has had unforeseen consequences on the delivery of HIV and sexually transmitted disease (STD) prevention services. However, little is known about how the pandemic has impacted pre-exposure prophylaxis (PrEP)-using men who have sex with men (MSM). METHODS: Data come from an online cohort of PrEP-using MSM in the Southern United States from October 2019 to July 2020. Participants were administered 10 surveys in total, including 1 ad hoc survey specifically on COVID-19. We conducted a cross-sectional analysis of this ad hoc survey (n = 56) and present changes in sexual behaviors and utilization of and access to sexual health services. Using linear mixed-effect regression models, we also analyzed data from the larger cohort and document how sexual behaviors and PrEP use varied longitudinally across several months. RESULTS: A fifth of participants discontinued or changed how often they take PrEP because of COVID-19. A quarter of the cohort documented challenges when attempting to access PrEP, HIV testing, or STD testing. For all sexual behaviors examined longitudinally-number of male sexual partners, anal sex acts, condomless anal sex, and oral sex (all measured in the past 2 weeks)-there was a decrease from February to April followed by an increase from April to June. DISCUSSION: Our findings suggest reduced access to and utilization of STD and HIV services coupled with a continuation of behaviors which confer STD/HIV risk. Ensuring appropriate delivery of STD/HIV prevention services during this pandemic is imperative.