Objective To investigate the value of MR apparent diffusion coefficient (ADC) and relative apparent diffusion coefficient (rADC) in differential diagnosis of lymphoma and metastasis in cervical lymph nodes.Methods Totally 69 patients with lymphoma (lymphoma group) and 66 patients with cervical lymph nodes metastasis (metastasis group) underwent MR examination.ADC values of lymph nodes and the right masseter muscle were measured,and rADC values were calculated.The consistency between two observers was evaluated.The differences of ADC value and rADC value were compared between the two groups.The efficacy of ADC value and rADC value in differential diagnosis of lymphoma and metastasis in cervical lymph nodes was analyzed with ROC curve.Results The consistency between two observers was excellent (all ICC＞0.9).Both ADC and rADC values of lymphoma group were significantly lower than those of metastasis group (all P＜0.05).Taken ADC and rADC values as 0.702 × 10-3 mm2/s and 0.584,the sensitivity and specificity was 98.48 ％ and 89.39 ％,76.81 ％ and 84.06 ％,respectively.Conclusion ADC and rADC values are useful in discriminating lymphoma from metastatic lymph nodes.