To evaluate the effects of tamoxifen on the growth and autocrine growth factor production of human dermal fibroblasts from the face. Methods: In vitro study of normal adult dermal fibroblast cells developed from surgical specimens in a serumfree model. Cell cultures were exposed to 5-, 8-, 12-, 16-, and 50-µg/mL concentrations of tamoxifen solution. Cell counts were performed, and the cell-free supernatants were collected at 0, 1, 3, 5, and 7 days after the initial exposure. Population doubling times were calculated, and supernatants were quantitatively assayed for basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF) ␤1. Results: Tamoxifen appears to delay cellular proliferation rates in a dose-dependent manner up to a concen