Retinoid X receptor (RXR) is a member of the nuclear receptor superfamily of ligand-activated transcription factors that have been characterized in a wide variety of species. In vertebrates, RXR functions as either homo-or hetero-dimers to regulate expression of target genes. RXR is important in a variety of physiological events including embryo development, cell-proliferation, metabolism and regeneration. The investigation of molluscan RXR is of particular interest due to its involvement in neogastropods imposex. In this review, we compared the amino acid sequence of molluscan RXRs with human RXRα and other vertebrate RXRs and performed phylogenetic analyses. Parsimony analyses of 22 invertebrate and vertebrate RXRs indicated that the molluscan RXRs were analogous to chordate RXRs. The alignment of amino acid of different isoforms of molluscs and crustaceans indicated that different cutting enzymes or splice sites should exist in T-box. In addition, we discussed the ligand, dimer partner, and physiological function of molluscan RXRs.