Fibrous hamartoma of infancy is a distinct clinicopathologic entity with unique microscopic findings and benign clinical course. This tumor is composed of intervening dense fibrocollagenous trabeculae, well defined mucoid areas and varying amounts of mature fat, which are arranged in organoid growth pattern. We report three typical cases of this tumor which were experienced during the recent two years at the Seoul National University Hospital. It is the first description on this tumor in Korean literature. Case 1 was a 10 month old boy who was admitted due to a mass in the right infra clavicular area for 6 months. The mass showed irregular and poorly circumscribed outer surface. Case 2 was a one month old girl who was presented with a diffuse ill defined hairy mass in the left buttock since birth. Case 3 was a 15 month old boy who was brought to the hospital due to well circumscribed scrotal mass fot 8 months. Microscopically all three cases showed very similar histological features. And all 3 cases are well after the removal of the tumors.