Abstract: Stomatocytosis, cup-shaped cell with a slit-like indentation, is an autosomal recessive trait which was reported from some dog breeds. A 4-day-old Holstein-Friesian female calf, which had been suffered tremendously from incomplete passive transfer of immunoglobulin, was referred to a veterinary hospital in a state of shock and lateral recumbency. The calf had been drenched with 150 mL of sulfadimidine by an inexperienced labor. Hematological findings demonstrated 50% stomatocytes in complete blood count and mild macrocytic normochromic anemia. Moreover, Wright's staining of RBCs shows 0.4% reticulocytosis. Despite supportive treatment, the animal didn't recover and died after 1 h. On microbiologic investigation, Escherichia coli were isolated from all tissues, body fluids and bone marrow. This case study has described in detail the first report of ruminant stomatocytosis in a Holstein-Friesian calf that was administrated by toxic dose of sulfadimidine (sulfamethazine) and suffered enormously from coli septicemia and meningitis.