We report here that epidermal growth factor (EGF) isolated from male mouse salivary glands is active as a potent chemoattractant for a rat heart vascular endothelial cell line (RHEC). Human EGF and transforming growth factor-alpha (TGF-alpha) produced in Escherichia coli are also active as chemoattractants for these cells. The chemotactic response of the cells is induced by concentrations of murine EGF that ranged from 0.01 to 1.0 nM with similar specific activities for both the human EGF and TGF-alpha. Other growth factors such as fibroblast growth factor (FGF), TGF-beta, platelet-derived growth factor (PDGF), insulin, or IGF were not active as chemoattractants for these cells. The chemotactic response exhibited similar kinetics to those reported for connective tissue cells responding to PDGF (2-6 h) and required both RNA and protein synthesis. However, in contrast to NIH/3T3 cells responding to PDGF, the proliferating cultures of RHEC respond as well as growth-arrested cultures in the chemotaxis assay. In in vivo studies of connective tissue regeneration it appears that EGF-like factors are present in wound fluid collected from rats. Acid extracts of wound fluid contained a RHEC chemotactic activity that was neutralized with anti-EGF antisera. These studies indicate that EGF-like factors may function in vivo to control in part the angiogenic events that occur during tissue repair.