Often when calcite is found as a component of urinary calculi, they are considered false calculi or artifacts. We present a case of true calcite urolithiasis. The stone material was removed percutaneously from a severely malnourished anorectic woman and analyzed by infrared spectroscopy (IRS). In addition, calcite urolithiasis was confirmed in several recurrent stone events by IRS. Laxative abuse with magnesium oxide was believed to be the underlying cause of stone formation, and ammonium chloride given as one weekly dose turned out to be effective for stone prevention.