Humanized or chimeric anti-CD47 monoclonal antibodies are provided. The antibodies bind to and neutralize human CD47, and find use in various therapeutic methods. Preferred are non-activating antibodies. Embodiments of the invention include isolated antibodies and derivatives and fragments thereof, pharmaceutical formulations comprising one or more of the humanized or chimeric anti-CD47 monoclonal antibodies; and cell lines that produce these monoclonal antibodies. Also provided are amino acid sequences of the antibodies.