Mobile genetic elements are often employed for constructing gene fusions or to perform mutagenesis. mariner transposons are well-suited to such applications because of their low site specificity, in vitro activity, and exceptionally broad host range. This report describes a mariner-based method for rapidly creating a large number of insertion mutants that can be converted to in-frame epitope fusions in a single step. First, a mariner-based vector is used to deliver a FLP recombinase substrate randomly into a target molecule. Expression of the FLP recombinase is then induced to catalyse the excision of sequences flanked by FLP recombinase target recognition sites, leaving behind a triple-FLAG epitope. The reversibility of the excision event provides opportunities for using genomic targeting methods easily to create transcriptional or translational fusions to genes of interest.