The conjugated goat anti-mouse polymer-alkaline phosphatase (AP) secondary antibody reacts with heavy and light chains on mouse IgG. It reacts with all mouse IgG subclasses and with mouse IgM. The innovative AP-polymerization technology provides a significant increase in staining sensitivity when compared to other conventional AP-conjugated secondary antibodies. Avidin-biotin blocking procedures are not necessary when using the MACH 2 conjugated secondary antibodies. The overall staining procedure uses one less reagent (streptavidin peroxidase) and rinsing step, eliminates avidin-biotin blocking procedures, and may reduce overall staining time. It can be used manually and on automated stainers.