A murine cell line, Swiss 3T3, is commonly used for the study of cellular growth. The present study revealed that this cell line possesses high-affinity receptors for endothelin, a vasoactive peptide derived from vascular endothelial cells. In this cell line, endothelin potentiated DNA synthesis stimulated by platelet-derived growth factor, basic fibroblast growth factor or insulin. The endothelin concentration required for potentiating DNA synthesis in this cell line is almost the same as that reported previously in endothelin-induced vasoconstriction. Since endothelin increased intracellular calcium levels, this ion may participate in the signal transduction pathways by which endothelin induces potentiation of DNA synthesis.