Abstract: The invention relates to ELISA kits for detecting pro-collagenase 3 and activated collagenase 3 in body fluids, especially in human serum and synovial fluid, and in cell culture supernatants, and monoclonal antibodies which specifically recognise said antigens. Said ELISA kit comprises the following separately packed elements: a) a solid carrier comprising monoclonal antibodies which are bound thereto and sensitively and specifically bind human procollagenase 3 or activated collagenase 3; b) human recombinant procollagenase 3 or activated collagenase 3 as a standard for the quantitative determination of said enzyme; c) a buffer for producing a standard series of the recombinant collagenase 3; d) a buffer for diluting the body fluids to be analysed; e) a conjugate which is marked in such a way that it can be detected and which binds to collagenase 3; and f) a substrate which enables the visualisation of said conjugate which is marked in such a way that it can be detected.