Renal vascular effects of cyclooxygenase and cytochrome P450 metabolites of arachidonic acid have been extensively studied, with major advances having been made. More recently, studies indicate that arachidonic acid metabolites of the lipoxygenase and cytochrome P450 pathway, such as hydroxyeicosatetraenoic acids and epoxyeicosatrienoic acids, play novel roles in glomerular mesangial and epithelial cells that are relevant to the pathogenesis of kidney disease associated with diabetes and hypertension. These studies demonstrate that eicosanoids generated during the actions of growth factors and vasoconstrictors can modulate disease processes by affecting vascular homeostasis, inflammation, cellular growth, apoptosis and oxidant stress. In addition, they highlight the important roles played by these oxidized lipids in mediating multiple physiological and pathological functions in the kidney through activation of key signal transduction pathways and genes.