BACKGROUND: Young adult heart transplant (HT) recipients transferring to adult care are at risk for poor health outcomes. We conducted a pilot randomized controlled trial to determine feasibility and test a transition intervention for young adults who underwent HT as children and transferred to adult care. METHODS: Participants were randomized to the transition intervention (4 months long, focused on HT knowledge, self-care, self-advocacy, and social support) or usual care. Self-report questionnaires and medical records data were collected at baseline and 3 and 6 months after the initial adult clinic visit. Longitudinal analyses comparing outcomes over time were performed using generalized estimating equations and linear mixed models. RESULTS: Transfer to adult care was successful and feasible (i.e., excellent participation rates). The average patient standard deviation of mean tacrolimus levels was similar over time in both study arms and < 2.5, indicating adequate adherence. There were no between group and within group differences in percent of tacrolimus bioassays within target range (>50%). Average overall adherence to treatment was similarly good for both groups. Rates of appointment keeping through 6 months after transfer declined over time in both groups. CONCLUSIONS: Feasibility of the study was demonstrated. Our transition intervention did not improve outcomes.