Emerging evidence shows that diffusion-weighted magnetic resonance imaging (DW MRI) and fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography (We assessed whether DW MRI is equivalent to PET/CT in lung cancer diagnosis and evaluation.The institutional review board approved this study, and written informed consent was obtained from all patients. DW MRI and FDG PET/CT were performed before therapy in 15 lung cancer patients diagnosed by pathological examination. Apparent diffusion coefficient (ADC), ratio of ADC (rADC = ADC in tumor/ADC in spinal cord) and maximal standardized uptake value (SUVADC, rADC and SUVBoth DW MRI and FDG PET/CT had similar limited diagnostic capability of predicting different histological types and malignancy of lung cancer. This study may help provide a novel insight into diagnostic and therapeutic strategies of lung cancer based on DW MRI.