['To examine the relationship of serum insulin-like growth factor (IGF)-1 and IGF binding protein-3 (IGFBP-3) with histological cancer characteristics in men undergoing transrectal ultrasonography (TRUS)-guided biopsy.', 'Patients (652), with either an elevated serum prostate-specific antigen level or an abnormal digital rectal examination, were initially evaluated by TRUS and sextant prostatic needle biopsy. Blood was drawn before biopsy, serum extracted and stored frozen until IGF-1 and IGFBP-3 were measured. In all, 241 patients had prostate cancer (37%) and were included in this study. The number of positive biopsies, the volume of tumour in each positive biopsy and the Gleason score were recorded.', 'Of the 241 patients, 37 had five or six positive biopsies (from six), 128 had two to four and 76 had one. Serum IGF-1 did not correlate with the number of positive biopsies, with means of 176.7, 178.3 and 164.4 ng/mL, respectively (P = 0.3), while the mean IGFBP-3 was 2695, 2795 and 2572 ng/mL, respectively (P = 0.09). The additive percentiles of tumour volume in positive biopsies were assessed for each patient but serum IGF-1 and IGFBP-3 did not correlate (P = 0.7 and 0.9, respectively). In all, 92 patients had a Gleason score of < 7, 80 a score of 7 and 69 a score of > 7; the mean (sd) IGF-1 levels for the three groups were 181 (39), 174.6 (35) and 176 (26) ng/mL, and the mean IGFBP-3 2798 (240), 2735 (284) and 2647 (221) ng/mL, respectively, none of the differences being statistically significant.'] Do serum insulin-like growth factor ( IGF ) -1 and IGF-binding protein-3 correlate with Gleason score or quantity of prostate cancer in biopsy samples?