Objective:To estimate trends in the proportion of sexually active U.S. adults with HIV (PWH) reporting an HIV-discordant sexual partner taking preexposure prophylaxis (PrEP) and proportion of partners taking PrEP.Design:The Medical Monitoring Project is a complex sample survey of U.S. adults with diagnosed HIV.Methods:We used annual cross-sectional data collected during June 2015-May 2020 to estimate the annual percentage change (EAPC), overall and by selected characteristics, in reported partner PrEP use among PWH with HIV-discordant partners (N=8707) and reported PrEP use among these partners (N=15 844).Results:The proportion of PWH reporting PrEP use by one or more HIV-discordant sex partner rose 19.5% annually (11.3 to 24.4%). The prevalence rose from 6.0 to 17.4% (EAPC, 25.8%) among Black PWH, 10.1 to 26.0% (EAPC, 19.5%) among Hispanic/Latino PWH, and 20.8 to 34.6% (EAPC, 16.3%) among White PWH. Among MSM with HIV, the prevalence increased from 9.6 to 32.6% (EAPC, 28.2%) among Black MSM, 16.6 to 36.0% (EAPC, 15.6%) among Hispanic/Latino MSM, and 24.9 to 44.1% (EAPC, 17.9%) among White MSM. Among HIV-discordant sex partners, the proportion reported to be taking PrEP increased 21.1% annually (7.8 to 18.8%). Reported PrEP use rose from 4.9 to 14.2% (EAPC, 29.9%) among Black partners, 6.5 to 16.8% (EAPC, 20.3%) among Hispanic/Latino partners, and 12.7 to 26.1% (EAPC, 17.0%) among White partners.Conclusions:One in five HIV-discordant sexual partners of PWH was reported to be taking PrEP. PrEP use rose among all examined populations, although the increases did not eliminate disparities in PrEP use.