Small G proteins exist in eukaryotes from yeast to human and constitute the Ras superfamily comprising more than 100 members. This superfamily is structurally classified into five families: the Ras, Rho, Rab, Arf and Ran families that control a wide variety of cell and biological functions through highly coordinated regulation processes. Among them, proteins of the Rho family are initially described as master regulators of the actin and microtubule cytoskeletons, thus regulating numerous cellular functions, including migration, membrane trafficking, adhesion, polarity and cell shape changes. However, increasing evidence has accumulated to identify Rho proteins and their regulators as key players of the cardiovascular physiology that control a large panel of cardiac (heart rhythm, contraction, hypertrophy) and vascular functions (angiogenesis, vascular permeability, vasoconstriction). Indeed, basal Rho protein activity is required for homeostatic functions in physiological conditions, but sustained over-activation of Rho proteins or spatiotemporal dysregulation of Rho signalling pathways has pathological consequences in the cardiovascular system. Both pharmacological studies, genetic approaches in human, mouse models with targeted mutations in Rho proteins or regulators genes enabled the analysis of Rho protein functions in vivo, demonstrating their involvement in the pathogenesis of several diseases, including hypertension, coronary vasospasm, stroke, atherosclerosis, heart failure and diabetes. Accordingly, Rho protein signalling pathway and Rho proteins effectors such as Rho kinases are considered as important new pharmacological targets for the next generation of therapeutic agents in cardiovascular medicine. The primary object of this lecture is to provide a comprehensive overview of the current progress in our understanding of the role of Rho proteins and their regulators in cardiovascular physiology and pathologies and describing challenges for the future.