Immunosuppression adherence among kidney transplant recipients is essential for graft survival. However, nonadherence is common, jeopardizing graft survival. Besides skipping dosages, little is known about other forms of medication nonadherence and their underlying reasons. This study was undertaken to examine patients' extent of medication adherence over time and reasons for nonadherence. Thirty-nine new kidney transplant recipients were asked to complete a month-long medication-taking diary that included reporting medication nonadherence such as skipped medications, medications taken early or late, taking dosages greater or less than prescribed, and the reason for each occurrence of nonadherence. Of the 20 (51%) patients who completed the diary, 11 (55%) reported at least one form of nonadherence. Eleven patients reported taking their immunosuppression at least one hour later than the prescribed time, one patient reported skipping medication, but no patients reported changing the dosage on their own. Immunosuppression was taken on average 1.5 hours after the prescribed time. Of those patients who took their medications late, there were on average 3.1 occasions of taking it late. The most common reasons for this behavior included health care related issues, followed by oversleeping, being away from home, work-related barriers, and forgetting. A large minority of kidney transplant recipients took medications later than prescribed during one month. Future research should determine the clinical impact on graft function of late administration of immunosuppression. Interventions should be designed to better assist kidney recipients with taking medications on time, especially when they are away from home.