To examine changes in HIV-positive patient enrollment in a large health care delivery system before and after key Affordable Care Act (ACA) provisions went into effect in 2014. Analyses compared HIV-positive patients newly enrolled in Kaiser Permanente Northern California between January and June 2012 (n?=?339) to those newly enrolled between January and June 2014 through the California insurance exchange or via other mechanisms (n?=?549). After the ACA, the HIV-positive patient enrollment increased. These new enrollees were more likely to be male (93.6% vs 89.1%; P?=?.01), to be enrolled in high-deductible benefit plans (??$1000; 18.8% vs 5.5%; P?=?.01), and to have better HIV viral control (HIV RNA levels below limits of quantification 79.5% vs 73.6%; P?=?.05) compared with pre-ACA new enrollees. Among post-ACA new enrollees, there were more patients in the lowest and highest age groups. Post-ACA exchange enrollees (22%) were more likely to be male and to have high-deductible plans than those enrolled through other mechanisms. More men, higher deductibles, and better HIV viral control characterize newly enrolled HIV-positive patients after the ACA in California. Evolving characteristics of HIV-positive enrollees may affect HIV policy, patient care needs, and service utilization.