Maximizing kidney transplant patients' long-term compliance with immunosuppressants is a major challenge to transplant coordinators. Although previous research has found substantial proportions of recipients to be noncompliant, predictors of noncompliance and characteristics of noncompliers remain unclear. In this study of more than 1400 kidney transplant patients, we found noncompliance to be associated with patient and transplant characteristics and with patient beliefs concerning the efficacy of immunosuppressants. Three distinct profiles of noncompliers were identified: accidental noncompliers, invulnerables, and decisive noncompliers. This information can be used by transplant coordinators to recognize cues that predict noncompliance and to work with at-risk patients to forestall or remedy noncompliant behavior.