Anti-GFP antibodies are useful reagents for the immunodetection of GFP (green fluorescent protein), a commonly used epitope tag for recombinant proteins in applications such as immunofluorescence, flow cytometry, or western blot. GFP is a 27-kilodalton protein first discovered in the jellyfish Aequorea victoria and features an amino acid sequence ranging from 236 to 246 residues. As a protein tag, GFP can be detected in cells both in vivo and in vitro for studies in gene expression. Antibodies to GFP are useful for boosting the tag's signal or for providing an additional mode of detection for the labeled protein.