The aim of this study is evaluating the contribution of diffusion-weighted MR imaging (DWI) in the final diagnosis of patient that parotid gland tumours has been determined. Fourty patients with 41 parotid masses were included to this study. The mean Apparent Diffusion Coefficient (ADC) values were calculated for all of lesions by performing DWI. 28 benign and 13 malignant tumours were detected as a final diagnosis. ADC values of these lesions were compared. The optimal cutoff ADC value was determined for discrimination of these lesions by using ROC curve analysis. The most often benign and malignant tumours of parotid gland were pleomorphic adenoma and secondary tumours, respectively. The highest ADC value as 2.10±0.26×10-3 mm²/sec was belong to pleomorphic adenoma. The mean ADC value of pleomorphic adenoma was significantly higher than other lesions. As a result of ROC curve analysis, pleomorphic adenomas were differentiated from all other benign and malignant tumours with 1.60×10-3 mm²/sec cutoff ADC value that had sensitivity of 94.7% and specificity of 100%; and also malignant tumours were differentiated from Warthin’s tumours with 1.01×10-3 mm²/sec cutoff ADC value that had sensitivity of 92.3% and specificity of 100%.We could differentiated pleomorphic adenomas, Warthin tumours and malignant tumours each other which are the most common parotid gland tumours by using the value of ADC.