Immunoglobulin IgG provides the majority of antibody-based immunity against invading pathogens and plays a significant role in the pathology of auto-immune diseases. Most mouse monoclonal antibodies are of the IgG isotype. Because mice are widely used as a research model for studies of the immune system, various diseases, and drug development, mouse monoclonal antibodies have become an important tool in biochemistry, molecular biology, and medicine. There are multiple applications for a sensitive assay to accurately quantify the concentration of mouse IgG in complex sample matrices. Cayman's Mouse IgG ELISA Kit is a sandwich assay that can be used to measure IgG in mouse plasma, mouse serum, cell culture supernatants, and ascites without prior sample purification. The standard curve spans the range of 1.6-100 ng/ml with an LLOQ of 1.6 ng/ml. The reported measured levels of IgG in mouse serum range between 2 and 22 mg/ml.