Severe anemia was found in a 4-month-old heifer, which was admitted with a 1-day history of anorexia, signs of depression, and recumbency. A diagnosis of immune-mediated hemolytic anemia (IHA) was made on the basis of a Coomb's titer of 1:128 and decreased resistance to osmotic stress, as determined by an RBC fragility test. Anaplasmosis and leptospirosis were ruled out as possible causes of the IHA. Other causes of hemolytic anemia, including intoxication by copper, water, Brassica spp, or drugs were ruled out. Therefore the IHA was considered idiopathic. Treatment consisted of supportive therapy, oxytetracycline, and dexamethasone. After 60 days of treatment, CBC, Coomb's test result, and RBC fragility were within normal limits.