A laminin-derived synthetic peptide, Cys-Asp-Pro-Gly-Tyr-Ile-Gly-Ser-Arg-NH2 (CDPGYIGSR-NH2), containing an active site for cell binding inhibited both angiogenesis and solid tumor growth. It potently suppressed both embryonic angiogenesis of the chick chorioallantoic membrane and migration of vascular endothelial cells induced by a tumor-conditioned medium but neither the in vitro proliferation of endothelial cells nor that of tumor cells. Additionally, in in vivo tests, CDPGYIGSR-NH2 markedly inhibited both the growth of s.c. solid tumor of Sarcoma 180 and that of Lewis lung carcinoma (3LL) in the lungs. On the contrary, ascitic tumor growth of Sarcoma 180 was not affected by this peptide, even though the same cell source was used. It was concluded that solid tumor growth inhibition by CDPGYIGSR-NH2 was due not to a direct effect on cell growth but to an antiangiogenic effect mediated by the inhibition of endothelial cell migration.