The present invention provides monoclonal antibodies, and portions thereof, which are capable of specifically binding to human vascular endothelial cell growth factor (hVEGF) or hVEGF-related protein. The invention also provides hybridoma cell lines that produce such monoclonal antibodies. The monoclonal antibodies of the invention are useful as therapeutic agents, either by themselves or in conjunction with cytotoxic or other chemotherapeutic agents, to treat diseases that are characterized by excessive vascular endothelial cell proliferation. The monoclonal antibodies of the invention also are useful in diagnostic and analytical methods for determining the presence of hVEGF or hVEGF related-protein in a test sample.