Type I insulin-like growth factor (IGF) receptors have been recently characterised in human colorectal cancers. The aim of this study was to determine whether type I IGF receptor concentration may be related to prognostic variables in colorectal cancers. Saturation experiments with [125I]IGF-I were performed on membrane preparations of 46 frozen specimens (20 tumours, 26 controls) and analysed according to the Scatchard method. In all the studied cases, we found a single class of high affinity binding sites in both normal and malignant colorectal tissues (median 0.17 and 0.15 nmol/l, respectively). Using paired analysis, we found no significant difference in terms of type I IGF receptor concentration between malignant and normal colorectal tissues. There was also no relationship between type I IGF receptors and any of the tumour characteristics studied. This study does not support a critical role of the type I IGF receptors in the clinical management of colorectal cancers.