Two cDNA clones of the soybean early nodulin GmENOD55 were characterized. These clones may represent two members of the soybean early nodulin gene family GmENOD55. GmENOD55 has an N-terminal signal peptide and it contains an internal domain consisting of proline and serine residues. Analyses of nodules lacking infection threads and intracellular bacteria suggest that the GmENOD55 gene is first expressed after release ofBradyrhizobium japonicum in plant cells. This conclusion is supported byin situ hybridization studies showing that the expression is restricted to the infected cell type.