Pericardial effusion and cardiac tamponade following renal transplantation have been recognized as a potentially serious complications associated with the use of sirolimus for immunosuppression. Our study aims to analyze the development of sirolimus-associated pericardial effusion. Patients who underwent renal transplantation at our institution between 2001 and 2014 were reviewed and the correlation between sirolimus exposure and pericardial effusion was determined. Nineteen out of 792 patients who received a renal transplant over this 14-year period (incidence 2.4%) developed symptomatic pericardial effusion (determined by the need for pericardiocentesis or a pericardial window). All patients had a pre-transplantation cardiac workup, including echocardiogram, which did not reveal the presence of pericardial effusion. Our cohort of patients is mostly male (57.9%) and Caucasian (73.7%), which is consistent with the makeup of transplant recipients at our center. The mean age was 52.42 years at the time of transplantation. The development of symptomatic pericardial effusions occurred at a mean of 5.06 (.5-9.8) years after renal transplant while on sirolimus therapy. Sirolimus levels at diagnosis were 5.19-7.47 ng/mL. No significant pericardial effusion (resulting in tamponade physiology) recurred after therapeutic intervention, including cessation of sirolimus with or without pericardial drainage. This study is the largest single-center report of the possible association between pericardial effusion in renal transplant recipients who received sirolimus. Due to the widespread use of sirolimus in organ transplantation, clinicians must remain vigilant for this potential cardiac complication.