A lagomorph derived monoclonal antibody for recognizing the progesterone receptor (PR) (clone SP2) with immunohistochemistry and methods for creating such an antibody are disclosed. No need of target retrieval in immunohistochemistry is their prominent advantage compared to currently available PR antibody. Furthermore, the very low background when the lagomorph derived monoclonal antibody is used in immunohistochemistry is also impressive. The immunohistochemistry comparative study with about fifty clinical specimens showed that the new PR antibody (clone SP2) antibody had favorable results when compared to mouse monoclonal antibody PR (clone 1A6), the best one in the current market. The PR antibody may prove of great value in the assessment of PR status in human breast cancer. Humanized versions of the PR antibody may provide therapeutic benefits.