Using a recently developed ELISA for free IGF-I [19], we measured free IGF-I levels in baseline serum samples from men who subsequently developed prostate cancer and their matched controls [median time to diagnosis: 14 years, interquartile range (IQR) = 2.9] in a large sample (767 pairs or n = 1534). This evidence concerns the gene IGF1 and prostate carcinoma.