Although magnetic resonance imaging (MRI) has been shown to be a promising technique for staging prostatic carcinoma, its accuracy in detection of extraprostatic spread and seminal vesical invasion is subject to considerable error. The role of dynamic MRI, following bolus intravenous contrast medium, in depicting carcinoma of the prostate was evaluated and the information provided by this technique compared with unenhanced images. Spin-echo T1-weighted, T2-weighted, bolus contrast enhanced and delayed post-contrast enhanced T1-weighted images were obtained in 20 patients with histologically proven adenocarcinoma of the prostate. Tumour was identified in all of the patients studied. When compared with unenhanced and delayed post-contrast enhanced images, dynamic bolus contrast enhanced images enabled the best definition of tumour within the gland in 50% of patients and demonstrated extracapsular spread more clearly in 80% of patients. It is concluded that dynamic bolus contrast enhancement may be useful in selected patients with prostatic carcinoma by enabling tumour margins to be depicted more clearly.