Hypercalcemia (12.0 to 18.3 mg/dl) was detected in 3 cats that had eaten a rodenticide that contained cholecalciferol. Clinical signs included lethargy, anorexia, vomiting, and polydipsia. Treatment with furosemide and fluids administered IV resulted in normalization of the serum calcium concentration and in remission of the clinical signs in 2 cats. One cat with a serum calcium concentration of 18.3 mg/dl did not have clinical signs, was not treated, and was reportedly normal 9 months after initial examination. We attributed the uniformly favorable outcome of exposure to the rodenticide in these cats to the small quantity of the toxin ingested.