IGF-1 levels increased, and IGF-2 and IGFBP-3 levels remained unchanged, in postmenopausal women following oophorectomy. The increase in IGF-1 likely results from decreased ovarian steroidogenic precursors resulting from removal of the hormonally active ovary. This finding raises concerns, given the association between increased IGF-1 and elevated colon cancer risk, and adds to the literature suggesting a potential benefit from ovarian preservation.