This study examined the prevalence of appointment noncompliance in 101 heart transplant recipients and how appointment noncompliance is related to patient profile and clinical risk. Appointment noncompliance was defined as patients not showing up at 1 or more planned clinic appointments (at a minimal frequency of every 3 months) during the previous year. Clinical variables were collected from medical files. Psychosocial variables were measured using established instruments. Medication noncompliance was assessed using electronic event monitoring. Paired t test, Wilcoxon 2-sample test, chi-square test, or Fisher exact test were used for statistical analysis as appropriate. The prevalence of appointment noncompliance was 7%. Appointment noncompliers were significantly younger, were less likely to live in a stable relationship with a partner, were more depressed, perceived their health as poorer, experienced more symptom distress, and had significantly more drug holidays. Fifty-seven percent of the appointment noncompliers experienced 1 or more late acute rejection episodes, compared to 2% of the appointment compliers. Appointment noncompliance is a critical behavioral risk factor in the occurrence of late acute rejection episodes in heart transplant patients. Patient profiles allow the identification of patients at risk for appointment noncompliance.