The invention relates to antibodies which bind to insulin like growth factor receptor-1 (IGF-1R) and uses thereof, in particular in the diagnosis and treatment of cancer. Specific human and murine monoclonal antibodies which inhibit IGF-1R-mediated pro-survival and tumor proliferation pathways, and variants, fragments, and derivatives thereof are provided. Also provided are specific human and murine monoclonal antibodies which block the ability of the ligands, insulin like growth factor 1 (IGF-1) and insulin like growth factor 2 (IGF-2) to bind to IGF-1R, as well as fragments, variants and derivatives of such antibodies. The invention also includes polynucleotides encoding the above antibodies or fragments, variants or derivatives thereof, as well as vectors and host cells comprising such polynucleotides. The invention further includes methods of diagnosing and treating cancer using antibodies of the invention.