Current treatment for disseminated prostate cancer, whether progressive or hormone-resistant, do not improve survival. Insulin growth factors (IGFs) are potent stimulants of prostate epithelial cells growth, their presence having been demonstrated in high quantities in several tumours such as lung, hepatoma, pheochromocytoma, malignant glioma and breast cancer. Local management of growth factors production could improve the results of second line therapy in hormone-resistant prostate cancer. Levels of IGF-I were determined by radioimmunoassay (RIA) in normal (n = 5), hyperplastic (n = 5) and tumoral (n = 8) prostate tissue. Presence of IGF-I is confirmed in all tissues (9.62 +/- 5.81; 8.32 +/- 7.81 and 6.02 +/- 1.42 ng/mg protein, respectively) but no significant differences are displayed among the three groups.