PURPOSE: To determine the CT findings by which between benign and malignant parotid tumors, may be differntiated. MATERIALS AND METHODS: The CT findings of 58 cases of parotid gland tumors confirmed by surgery and histopathology were retrospectively analyzed by two radiologists ; there were 42 cases of benign and 16 of malignant tumors. CT findings for differentiation were location, size, density, margin, calcification within tumors, necrosis, cystic change, invasion of extraglandular structure and lymphadenopathy. RESULTS: In benign parotid tumors, the margins of mass were clear in 34 cases(81%), irregular in 3 (7%), and indeterminate in 5(12%). Necrotic changes were seen in 24 cases (57%) and lymphadenopathy in 1 (2%), but there was no extraglandular invasion. In 38 of 42 benign tumors the CT diagnosis for benignancy was correct. In malignant tumors, the margins were irregular in 11 cases (69%) and clear in 5 cases (31%). Evidence of extraglandular extension was seen in 6 cases (38%) and lymphadenopathy in 2 cases (13%). The CT diagnosis for malignancy was correct in 11 of 16 cases. CONCLUSION: Irregularities in tumor margin and findings of extraglandular extension are the most helpful indicators by which benign and malignant parotid tumors may be differentiated.