The purpose of this study was to retrospectively assess the diagnostic performance of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced imaging (DCEI) at 3T in predicting locally recurrent prostate cancer after radiation therapy. Twenty-four patients with a rising prostate-specific antigen level after treatment with radiation therapy underwent prostate MR imaging at 3T, followed by transrectal ultrasound-guided biopsy. MRI findings and biopsy results were correlated in six prostate sectors of both peripheral zones. Two radiologists in consensus reviewed the MR images and rated the likelihood of recurrent cancer on a 5-point scale. Out of the 144 prostate sectors, 37 (26%) sectors were positive for cancer in ten patients. For predicting locally recurrent cancer, the sensitivity and specificity of DWI, DCEI, and combined DCEI and DWI were higher than those for T2-weighted imaging (T2WI). The accuracy of DWI, DCEI and combined DCEI and DWI was greater than that of T2WI. A significantly greater Az was determined for combined DCEI and DWI (Az = 0.863, P < 0.05) as compared with T2WI, DCEI, and DWI. For predicting locally recurrent prostate cancer after radiation therapy, our preliminary results suggest that the use of either DWI or DCEI is superior to the use of T2WI.