Abstract: Antisense oligonucleotides optionally stabilized with phosphorotioate residues or analogues, or modified in the whole sugar-phosphate backbone--complementary to the human urokinase receptor messenger RNA--are able to prevent invasiveness of neoplastic cells by inhibiting the overexpression of the receptor itself, directly responsible of the invasive phenotype. Said oligomers are useful as medicaments for the treatment of primary and secondary neoplasias as well as of other pathologies wherein the urokinase receptor gene overexpression is a pathogenic event.