To our knowledge, this is the first reported case of an angiomatous lymphoid hamartoma in an infant. Because of a histologic pattern similar to thymoma and because it has most often been found in the mediastinum, this unusual tumor has had a confusing clinical and pathologic history. The clinical course is usually benign and self-limiting although on occasion there is an associated iron-refractory anemia, hyperglobulinemia, and growth retardation. Resolution of these symptoms has been reported to occur following surgical excision of the lesion. Our patient was seen at age 4 months with a palpable axillary mass. Following surgical excision the child has remained asymptomatic for three years.