Abstract: Few studies have examined the prevalence, demographic variables and adverse consequences associated with non-adherence to immunosuppressive therapy in the adolescent liver transplant population. Our hypothesis is that a significant proportion of adolescent liver transplant recipients exhibit non-adherence to medical regimens and that certain demographic and medical condition-related characteristics can be identified as potential predictors of non-adherent behavior. Furthermore, non-adherence leads to a greater incidence of morbidity and mortality in this population as compared with the adherent subset of adolescent patients. We reviewed the charts of 97 patients from 1987 to 2002 who by December of 2002 had survived at least 1 yr post-transplant and were followed by the Pediatric Liver Transplant Service at any point during their adolescent period (ages of 12–21). Non-adherence was defined as documentation of a report of non-adherence by a patient, parent or healthcare provider that was recorded in the patient's legal medical record. Descriptive statistics were used to determine the prevalence, demographic variables and adverse outcomes associated with non-adherence to immunosuppressive therapy. Categorical variables were analyzed using the chi-square test or the Fisher exact probability test. The unpaired Student's t-test was used to analyze the continuous variable of age at transplant. Using the inclusion criteria, a total of 97 patients represented the study sample of whom 37 subjects (38.1%) were defined as non-adherent and 60 (61.8%) were adherent. Non-adherent subjects were more likely to be female, older (>18 yr) and from a single-parent household. There was no significant difference in immunosuppressive regimen between non-adherent and adherent patients. Non-adherence was significantly (p<0.025) associated with lower socioeconomic status (SES), older age at transplant (p<0.005, 95% CI: −5.5 to −.99, Student's t-test) and episodes of late acute rejection (p<.001). Non-adherence was also significantly associated with re-transplantation and death secondary to chronic rejection by the Fisher exact test (p<0.006 and p<0.05, respectively). Non-adherence to immunosuppressive therapy is a prevalent problem that is correlated with certain demographic and medical condition-related risk factors and more frequent adverse consequences in the adolescent liver transplant population. The greater incidence of late acute rejection, death and re-transplantation owing to chronic rejection in non-adherent patients suggests that non-adherence is significantly associated with an increased risk of morbidity and mortality. Further investigation to identify patients at greatest risk for non-adherence is necessary to design the most effective intervention to increase patient survival and well being.