The ability of the Drosophila transposable element mariner to transpose in the chicken was tested using a plasmid carrying an active mariner element injected into chick zygotes. Surviving embryos and chicks were analyzed for presence of mariner. Analysis of embryos that survived for at least 12 days of development indicated that mariner had transposed at high frequency into the chicken genome. Germline transmission of mariner from one of three surviving birds confirmed transposition. Analysis of the first-generation (G1) chicks showed that they each contained between one and three copies of mariner. Six different transposition events were represented in the G1 birds, and the transposition was catalyzed by expression of the mariner element's transposase gene. Transmission from G1 to G2 occurred at a 1:1 ratio. Mariner therefore has potential for development as a vector for transgenesis in avian species.