Background: Labetalol is a commonly used agent for perioperative hypertension in renal transplant recipients. A previous report suggested that labetalol may cause life-threatening hyperkalemia after renal transplantation. Methods: We performed a retrospective review of 103 consecutive renal transplants to determine whether labetalol was an independent predictor of hyperkalemia treatment. Thirty-eight patients (36.9%) received labetalol, and 65 patients (63.1%) had no labetalol medication. Results: Of the 103 patients, 24 (23.3%) required treatment for hyperkalemia. Thirteen (34.2%) of the patients who had labetolol medication and 11 (16.9%) of the patients who did not receive labetalol were treated for hyperkalemia (p = 0.045). Factors considered for a logistic regression model included: the use of labetalol, cold ischemia time, diabetes, and dialysis method; intake of tacrolimus, beta blockers, angiotensin-converting enzyme inhibitors, or other antihypertensives prior to admission; the mannitol dose given intraoperatively, and the 24-hour urine output postoperatively. Intravenous labetalol (odds ratio OR = 4.52, confidence interval CI = 1.33–15.28; p = 0.02), 24- hour urine output (OR = 4.4, CI = 0.97–20.1: p = 0.47), increasing cold ischemia time (OR = 1.09, CI = 1.01–1.17; p = 0.02), and continuous ambulatory peritoneal dialysis (OR = 0.17, CI = 0.29-0.98; p = 0.036) were independent predictors. Conclusion: Labetalol appears to increase the risk of hyperkalemia in patients after renal transplantation.