Mucormycosis is characterized by severe infection with rapid progression and a high mortality rate. In immunocompromised hosts, the most common type is the rhinocerebral form of mucormycosis. Invasive mucormycosis affecting only the tongue is extremely rare. We report one such case that occurred in an immunocompromised 4-month-old girl with Down syndrome who had been hospitalized for acute gastroenteritis. The infant had metabolic acidosis secondary to diarrhea. It was suspected that the infection had been contracted through the use of a wooden tongue depressor during oral examination. We present this case report in the hope that it will discourage clinicians from using wooden tongue depressors in vulnerable infants. We also wish to emphasize that mucormycosis should be considered in all patients—regardless of age—who pre-sent with localized bluish-black discolored mucosa of the oral mucosa and/or tongue.