PURPOSE: This study was performed to evaluate the usefulness of diffusion tensor imaging (DTI) and to correlate systemic twelve biopsy in prostate cancer. MATERIALS AND METHODS: Thirty-one patients with suspected prostate cancer underwent MR imaging. DTI was performed prior to a prostate biopsy. We prospectively calculated the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) value in each corresponding biopsy site. RESULTS: Twenty-three of 31 patients had histopathologically proven adenocarcinoma. Among the 276 biopsy cores of 23 patients with prostate cancer, 109 cores showed positive results (39%). The ADC and FA value of positive cores were 1.31 +/- 0.34x10(-3) mm2/s and 0.68 +/- 0.07, and those of the negative cores were 1.74 +/- 0.45x10(-3) mm2/s and 0.54 +/- 0.09, respectively. Eight patients without carcinoma showed an ADC value of 1.83 +/- 0.26x10(-3) mm2/s and an FA value of 0.47 +/- 0.07. The ADC and FA value of positive cores were significantly lower and higher than those of negative cores and cancer-free patients, respectively (p < 0.05). CONCLUSION: The ADC and FA values using DTI may provide useful diagnostic information in the differentiation of cancerous tissues, although there is overlap in some cases.