Abstract: Abstract In recent years, small G proteins have become an intensively studied group of regulatory GTP hydrolyses involved in cell signaling. The small G-protein superfamily includes Ras, Rho, Rab, Arf and Ran homologs, which take part in numerous and diverse cellular processes, such as gene expression, cytoskeletal reorganization, microtubule organization, and vesicular and nuclear transport.These proteins, functioning as molecular switches, share a common structural core, described as the I-IV domain, and significant sequence similarity. The Arabidopsis genome contains 93 genes that encode small GTP-binding protein homologs. Phylogenetic analysis of these genes shows that plants contain Rab, Rho, Arf, and Ran GTPase but not Ras GTPase. In this paper, we review the known functions of individual members of these small GTPases in plants. Additionally, we describe the possible roles of these GTPases in relation to their similarity to orthologs with known functions in yeast or animal systems.