This study examined parental psychological functioning, illness severity, and medical adherence in parents of pediatric heart transplant patients. It was hypothesized that parental psychological distress would be associated with increased illness severity and medical non-adherence. Data were collected on 52 parents of pediatric heart transplant patients through the use of parent report questionnaires, cardiologist ratings, medication levels, and medical chart review. Results indicated that 19% of parents met DSM-IV clinical criteria for Post-Traumatic Stress Disorder. When compared with a normative adult population, the study population had significantly higher rates of general psychological distress. Furthermore, 38% of parents were non-adherent on at least one measure of medical adherence. Analyses examining the relationships among parental psychological distress, illness severity, and medical adherence did not identify any statistically significant associations; however, a medium effect size was found for the relationship between global psychological distress and non-adherence. Study limitations and implications for future research are discussed.