Primary malignant melanoma of the nasal cavity or paranasal sinuses is a relatively rare tumor. This forms of malignancy are characterized by their rapid spread and poor prognosis with a five years survival of 30 percents. The authors have recently experienced a case of primary malignant melanoma originated in the left nasal cavity. The patient had treated by wide excision of the tumor through nasopharynx and left nostril, and postoperative irradiation by Co60 with good result. We report a case of primary malignant melanoma in the left nasal cavity of 40 years old female patient with brief review of the literatures.