Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) method and is considered potentially useful for detecting prostate cancer. We evaluated the clinical value of DWI with apparent diffusion coefficient (ADC) maps in addition to T2-weightcd imaging (T2WI) using 3 tesla (3 T) MRI. Thirty-three patients with elevated prostate specific antigen were evaluated by MRI with T2WI and DWI prior to transperineal template-guided mapping biopsy. The MRI findings were compared with the pathology of biopsy specimens in six parts of prostate: both sides of outer peripheral zones, inner peripheral zones, and transition zones. The sensitivities, specificities and accuracies were 42.1, 84.4 and 76.3% in T2WI, 57.1, 84.7 and 80.8% in T2WI/DWI, and 87.5, 85.2 and 85.4% in DWI/ADC using 0.951 × 10 -3 mm 2/s as cutoff ADC value. The hazard ratio of patients whose ADC values were under the cutoff was 25.86 by multivariate analysis. Mean ADC values were significantly different between cancer positive and negative cores (p &lt
0.001). The ADC value showed a negative correlation with increasing tumor length (p = 0.0047). Although further study with a large number of patients is necessary, DWI/ADC using 3 T MRI is a useful tool for detecting prostate cancer.