Human essential hypertension is a complex, multifactorial, quantitative trait under polygenic control. The fundamental hemodynamic abnormality in hypertension is increased peripheral resistance due primarily to changes in vascular structure and function. These changes include arterial wall thickening and abnormal vascular tone, and are due to alterations in the biology of the cellular and noncellular components of the arterial wall. Multiple interacting humoral and mechanical factors as well as oxidative stress stimulate complex signalling pathways, which modulate vascular smooth muscle cell contraction and growth. Under normal physiological conditions, these finely regulated processes maintain vessel wall integrity and prevent pathological increases in blood pressure. However, under abnormal conditions, increased humoral and mechanical signalling results in vascular wall thickening and increased vascular tone, which play an important role in the pathogenesis and maintenance of hypertension. The present review discusses recent developments in the understanding of cellular and molecular mechanisms underlying vascular regulation in hypertension.