Abstract: A method for determining chondrocalcin through an immunoassay using an enzyme(s)-labeled mammalian chondrocalcin or enzyme(s)-labeled anti-chondrocalcin antibody which is characterized by that mammalian body fluid is used as a specimen and immunoreaction in a solution is utilized to determine the chondrocalcin of the mammalian, reagents and a kit therefor.This determination can be utilized for diagnosis or the like for cartilage-relating diseases in mammals.