The McKittrick-Wheelock syndrome is a very rare complication of rectal villous adenoma, characterized by fluid and electrolyte hypersecretion from a rectal tumour, which can lead to acute renal failure. We present a case review of a 67-year-old male patient hospitalised for profuse secretory diarrhea, with electrolyte dysbalance and progressive renal failure. A rectoscopic finding of massive rectal adenoma contributed to establishing the correct diagnosis. Resection of the affected part of the rectum resulted in rapid restoration from mineral imbalance and improvement of renal functions. The reported case shows the necessity of interdisciplinar management and the importance of surgical treatment in patients with this rare diagnosis.