The present invention relates to novel antibodies capable of binding specifically to the human insulin-like growth factor I receptor IGF-IR and/or capable of specifically inhibiting the tyrosine kinase activity of said IGF-IR receptor, especially monoclonal antibodies of murine, chimeric and humanized origin, as well as the amino acid and nucleic acid sequences coding for these antibodies. The invention likewise comprises the use of these antibodies as a medicament for the prophylactic and/or therapeutic treatment of cancers overexpressing IGF-IR or any pathology connected with the overexpression of said receptor as well as in processes or kits for diagnosis of illnesses connected with the overexpression of the IGF-IR receptor. The invention finally comprises products and/or compositions comprising such antibodies in combination with anti-EGFR antibodies and/or compounds and/or anti-cancer agents or agents conjugated with toxins and their use for the prevention and/or the treatment of certain cancers.