The human total Immunoglobulin G (IgG) competitive ELISA assay kit quantitates IgG in human samples such as serum or plasma. IgG is to be coated in the wells of the supplied microtiter plate overnight, where after samples preincubated with enzyme-linked goat-anti human IgG, standards and controls are added to the wells and bind to the immobilized IgG. A substrate solution is added that reacts with the enzyme-labelled target complex and a colorimetric measurable signal is produced. The intensity of the colorimetric reaction is directly proportional to the concentration of human IgG in the analysed sample.