In this descriptive cross-sectional study, we investigated the incidence, determinants, and consequences of subclinical noncompliance with immunosuppressive therapy in 150 adult renal transplant recipients with more than one year posttransplant status. Symptom frequency and symptom distress, and self-care agency were measured by the Transplant Symptom Frequency and Symptom Distress Scale, and the Appraisal for Self-Care Agency Scale, respectively. The Long-Term Medication Behavior Self-Efficacy Scale and a renal transplant knowledge questionnaire were developed as part of this study to measure perceived self-efficacy and knowledge of the therapeutic regimen. Demographic variables were also measured. The incidence of subclinical noncompliance with immunosuppressive therapy as assessed by interview was 22.3%. Compliers and noncompliers differed significantly on the variables of marital status (P = 0.03), situational-operational knowledge (P = 0.02), self-care agency (P = 0.03), and perceived self-efficacy related to long-term medication intake (P = 0.048). A logistic regression model using gender, marital status, perceived self-efficacy, self-care agency, knowledge about medication administration and signs of infection, and situational operational knowledge as predictor variables, revealed a 78.6% correct classification of compliers versus noncompliers and a sensitivity ratio of 95.9%. There were significantly more acute late rejection episodes (P = 0.003) in the noncompliant group. Graft survival at 5 years in this group was also significantly lower (P = 0.03) than the compliant patients. No significant difference was found in terms of the occurrence of chronic rejection episodes or in terms of patient survival at 5 years. Because noncompliance is a risk factor for negative clinical outcome in renal transplant recipients, it is of utmost importance to develop intervention strategies to enhance compliance in this population by using determinants identified in exploratory studies.