The proteoglycan versican plays multiple roles in cancer progression, from promoting cell invasion and proliferation to evasion of immune surveillance. Metalloproteinases of the A Disintegrin and Metalloproteinase with Thrombospondin-like motif (ADAMTS) family cleave versican at a specific Glu-Ala bond, thus releasing a bioactive fragment named versikine, whose biological function, still not entirely revealed, seems that of antagonizing the effects of the parental molecule. Here we describe an enzyme-linked immunosorbent assay (ELISA) that specifically detects versikine in media, pure component systems, and biological fluids using neoepitope antibodies. Such antibodies recognize their target proteolytic fragment but not the intact, parental molecule. Versikine fragments are captured by neoepitope antibodies and detected by antibodies directed against its N-terminal globular (G1) domain. The method here described can therefore be used to measure ADAMTS versicanase activity and provides a quantitative alternative to immunoblotting.