BACKGROUND: Evidence on prevalence and correlates of pretransplant medication nonadherence (MNA) is limited. The present study explored self-reported prevalence and correlates of MNA before heart, liver, and lung transplantation. METHODS: This cross-sectional descriptive study included 174 patients: 69 lung, 33 heart, and 72 liver transplant candidates. MNA was assessed by self-report using the following question: "During the past 14 days, how often did you not take your medication?" Patients scoring once or higher on a five-point rating scale were considered to be nonadherent. Correlates of MNA explored were demographics, anxiety and depression (Hospital Anxiety and Depression Inventory), personality traits (NEO Personality Inventory-Revised), perceived health status (Euro-QOL), and social support (Social Support Questionnaire). RESULTS: Prevalence of pretransplant MNA was 16.7% and was comparable among the three groups. After correction for multiple comparisons (i.e., P=0.01), higher educational level (P=0.006) was related to MNA. Less severe depression (P=0.069), lower scores on the personality trait conscientiousness (P=0.021), and less received social support (P=0.062) tended to be related to MNA. Multiple logistic regression revealed that higher educational level (P=0.008), lower received social support (P=0.013), and lower conscientiousness (P=0.023) were independent predictors of pretransplant MNA. CONCLUSIONS: Several correlates of MNA allow identification of patients at risk for pretransplant MNA.