Twenty-two patients with prostatic carcinoma have been studied by magnetic resonance imaging (MRI). Twenty-three examinations have been done for 2 stage A, 11 stage B, 2 stage C and 7 stage D. Prostatic signal and locoregional extension have been compared with rectal examination and the 3 prostatectomies. Cancer looked homogeneous in 4 cases, heterogeneous in 10 cases with a nodule in 5 cases either with hyper of hyposignal compared to the normal prostate. Local extension in stages C and D is seen, especially to the periprostatic fat and seminal vesicles. MRI appears to be sensitive but poorly specific in the diagnosis of prostatic cancer. On the other hand, it is an interesting examination in the staging of prostatic cancer. These results must be confirmed with more comparisons of images and prostatectomy specimens.