GW182 is a mRNA binding protein characterized by 60 repeats of glycine (G):tryptophan (W) motifs and is localized in cytoplasmic structures referred to as GW bodies (GWBs). Current evidence suggests that this unique protein plays a role in mRNA processing. To enable a more detailed study of GW182 and GWBs in cells and tissues, including their role in mRNA processing, we developed four monoclonal antibodies (MAbs) that bind the human recombinant GW182 protein. These MAbs can be used for Western blot analysis and indirect immunofluorescence (IIF) on cultured cells and tissues. Of special interest, one of the MAbs, 2D6, can be used to identify GW182 and GWBs in formalin-fixed and paraffin-embedded tissues after using an antigen retrieval method (ARM). All the MAbs described in this study immunoprecipitate the GW182 protein. Epitope mapping using overlapping 15-mer peptides representing the full-length GW182 showed that the major antibody-binding domains of these MAbs are distinct. These MAbs are valuable tools for cell biologists and pathologists to study the location and function of the novel GW182 protein in tissue culture cells, as well as cryopreserved or archived tissues.