Chondromyxoid fibroma (CMF) is a relatively rare bone tumor that was first described by Jaffe and Lichtenstein in 1948. CMF of the sinonasal tract is very rare. A 28-year-old male presented with long-standing, intermittent, pulsatile pain in the right temporal area. A computed tomography scan showed a 20 x 19 mm round, bony density in the right ethmoid sinus with fluid collection in the ethmoid and frontal sinuses. Additionally, a cystic lesion with surrounding edema was found in the right frontal lobe. The patient underwent a partial ethmoidectomy and frontostomy. A histological examination showed polygonal and stellate cells in a myxoid and chondroid background with a pattern of lobulation and plaque-like calcification. The bone lesion was revealed as a CMF of the ethmoidal sinus, and the frontal lobe cystic lesion was a brain abscess associated with the CMF. We present the case of a CMF of the ethmoid sinus complicated by a brain abscess.