Background <p>Although there are many long-term prophylactic treatments available for hereditary angioedema, few studies have assessed patient preferences for these treatments.</p> Objective <p>We aimed to assess patient preferences for long-term prophylactic treatment attributes, including treatment trade-offs and the likelihood of starting or switching to a new treatment.</p> Methods <p>An online discrete-choice experiment survey instrument was developed and administered to adults in the USA with a self-reported diagnosis of hereditary angioedema. Respondents evaluated a series of choices between pairs of hypothetical long-term prophylactic hereditary angioedema treatment alternatives.</p> Results <p>A total of 250 respondents (81.6% female; mean [standard deviation] age, 39 [11] years) completed the survey. Respondents placed the most importance on a reduction in attack frequency (conditional relative attribute importance =&#xa0;31.7%), a reduced risk of a gastrointestinal side effect (conditional relative attribute importance =&#xa0;18.5%), and treatments taken as an oral tablet compared with injections (conditional relative attribute importance =&#xa0;18.1%). Respondents were more willing to accept increases in injection-site reactions compared with their willingness to accept gastrointestinal side effects in these trade-offs. A total of 197 respondents (78.8%) stated they were open to starting a new medication with their preferred mode of administration.</p> Conclusions <p>A reduction in attack frequency is the most important treatment feature for adults living with hereditary angioedema. The heterogeneity in patient perspectives highlights the need for patient-physician communication when making decisions about initiating a new long-term prophylactic treatment for hereditary angioedema.</p>