Endoglin (CD105) is the marker of endothelial and mesenchymal stem cells and the component of TGF-β, BMP-9 and BMP-10-binding receptor complexes. Its expression is significantly increased on blood vessels endothelium of ischemic tissues and growing tumors. Measurement of concentration of the soluble endoglin in the serum or urine is used as a method for diagnosing cancer and pregnancy disorders. The aim of this work was to create a novel family of monoclonal antibodies recognizing endoglin on the cell surface and in biological fluids. Murine myeloma cells' derived recombinant protein representing the whole extracellular part of endoglin was used as an antigen. F1(SJL/JxBALB/c) mice were the donors of immune splenocytes. Hybridoma screening procedures were performed using E. coli-produced copies of the antigen, endoglin-expressing immortalized human cell lines, and primary cultures of human mesenchymal stromal cells. Ten novel monoclonal antibodies recognizing at least eight distinct epitopes were produced. Eight antibodies bind membrane form of endoglin on the surface of normal and transformed human cells derived from different tissue sources. Two antibodies recognize linear antigenic determinants of the molecule and can be used to detect endoglin by western blot. Sandwich ELISA system was designed in order to measure soluble endoglin in cell culture medium.