Hyperkalemia is not uncommon in patients with end-stage renal disease (ESRD) on maintenance hemodialysis, often related to dietary indiscretion, following the prolonged inter-dialytic weekend interval in patients on thrice weekly hemodialysis treatments, and sometimes the adverse effects of medications such as RAAS blocking agents. Moreover, hyperkalemia following extended cardiac surgery can result from the use of high-potassium containing cardioplegic solutions used during cardiopulmonary bypass. Nevertheless, different from the foregoing, in the nephrology literature, there have been very rare reports of potentially life-threatening hyperkalemia following cardiac valve replacement procedure. We recently encountered an unusual case of persistent relapsing hyperkalemia complicating aortic valve replacement (AVR) in a 53-year-old obese Caucasian male patient despite repeated daily intermittent hemodialysis treatments. Our case report is the first to clearly demonstrate the yo-yo recurrence of newly observed episodes of hyperkalemia reappearing despite repeated treatments.