OBJECTIVE: To report a case of congenital tongue-base hamartoma in a child treated at the University Hospital of Brasília, Brazil. CASE REPORT: A 10-month-old, female infant with no significant medical history was referred for a 1.0-cm tongue base and a pedunculated mass that had been present since birth. The child was underweight and was not feeding well. Surgical excision was performed and histopathology revealed a nodule with stromal and epithelial components. The stromal component was predominantly smooth muscle with adipocytes and periphery fibroblasts. The epithelial component was predominantly salivary gland mucous acini with ecstatic ducts. Hamartoma is defined as a growth of normal tissues endogenous to the development site. Most of the cases reported in literature affect the posterior region of the tongue. Clinically, it presents as a small asymptomatic, sessile, or pedunculated mass not exceeding 1.5 cm in diameter, and is usually present from birth. The histopathologic picture is described as a proliferation of unencapsulated smooth muscle within the subepithelium region. These muscle bundles are organized irregularly and can be mixed with nervous, lymphatic, or vascular tissue. In addition, salivary gland or adipose tissue may be present. The definitive treatment is surgical excision and there is no report of recurrence after excision in the literature. CONCLUSION: A tongue leiomyomatous hamartoma is a rare lesion, but it must be considered as a differential diagnosis for midline tongue masses near the foramen cecum. Treatment is surgical and no recurrence has been reported.