Immunoglobulins (Ig) are critical components of the immune system and play a major role in eliciting the body's immune response against pathogens. Five heavy-chain isotypes (IgA, IgD, IgE, IgG, and IgM) mediate specific biological functions, including responses to pathogens and immunological diseases such as allergies and autoimmune disorders. IgG, a monomer, is the dominant immunoglobulin class present in serum. There are four subclasses of IgG, namely IgG1, IgG2, IgG3, and IgG4. IgG is commonly used in research of humoral immunodeficiencies, autoimmune diseases, liver diseases, chronic inflammatory diseases, haematological disorders, infections, and lymphoid malignancies. This kit provides the assay-specific components for the quantitative determination of IgG in human, cynomolgus monkey, and rhesus monkey samples.