The present study examines adult human brain tissue for the presence of receptors for insulin-like growth factors (IGFs) 1 and 2 and insulin. Binding sites for all hormones were widely distributed throughout the brain removed at autopsy, with the highest specific binding being found in the various cortical regions. Cross-reaction studies performed on frontal lobe biopsy material indicated specific binding sites for IGF-1 and insulin whereas iodinated IGF-2 was equally displaced by IGF-1 and IGF-2, suggesting the presence of an additional IGF-2-like binding site in the adult brain.