Background: Traumatic ulcer is a common form of ulceration occured in oral cavity caused by mechanical trauma, either acute or chronic, resulting in loss of the entire epithelium. Traumatic ulcer often occurs in children that are usually found on buccal mucosa, labial mucosa of upper and lower lip, lateral tongue, and a variety of areas that may be bitten. To properly diagnose the ulcer, dentists should evaluate the history and clinical description in detail. If the lesion is allegedly accompanied by other infections, such as fungal, bacterial or viral infections, microbiological or serological tests will be required. One of the initial therapy given for fungal infection is nystatin which aimed to support the recovery and repair processes of epithelial tissue in traumatic ulcer case. Purpose: This case report is aimed to emphasize the importance of microbiological examination in suspected cases of ulcer accompanied with traumatic fungal infection. Case: A 12-year-old girl came to the clinic of Pediatric Dentistry, Faculty of Dentistry, University of Indonesia on June 9, 2011 accompanied with her mother. The patient who had a history of geographic tongue came with complaints of injury found in the middle of the tongue. The main diagnosis was ulcer accompanied with traumatic fungal infection based on the results of swab examination. Case management: This traumatic ulcer case was treated with Dental Health Education, oral prophylaxis, as well as prescribing and usage instructions of nystatin. The recovery and repair processes of mucosal epithelium of the tongue then occured after the use of nystatin. Conclusion: It can be concluded that microbiological examination is important to diagnose suspected cases of ulcer accompanied with traumatic fungal infection. The appropriate treatment such as nystatin can be given for traumatic fungal infection.