The current study sought to obtain a longitudinal perspective of and quantitatively assess barriers to medication adherence experienced by college students with attention-deficit/hyperactivity disorder (ADHD). Thus, we examined semester-long trends in barriers to adherence in addition to the relationships between barriers and medication adherence and barriers and quality of life.Participants were college students diagnosed with ADHD. Throughout a Fall semester, participants completed 4 sets of online questionnaires and attended 4 in-person visits, which included pill counts and written questionnaires. Participants completed measures assessing barriers to adherence and health-related quality of life, and adherence was measured via pill counts. Mean values of barriers, adherence rate, and quality of life were used for all analyses.Of the 45 students surveyed, mean adherence rate was 56.70%, and 84.45% of participants reported at least 1 barrier. Across the semester, participants reported experiencing an average of 3.07 barriers, and a consistent barrier reported was not realizing when pills run out. Although reported barriers were unrelated to adherence, the results showed that barriers were associated with lowered quality of life, specifically lower overall quality of life in addition to lower emotional functioning, psychosocial health, school functioning, and physical functioning.Barriers to adherence appear to be common in college students with ADHD, and certain barriers are consistent with the planning difficulties observed in individuals with ADHD. Because students experiencing more barriers had lower quality of life, interventions are needed to improve students' overall illness management experience.