In aggregate, the evidence reviewed here supports a very important role for PDGF expression and action at local glomerular and interstitial sites in human kidney development and disease. PDGF delivered by platelets, or produced by endogenous cells of the kidney is capable of stimulating responses including proliferation, matrix deposition, chemotaxis, and contraction in renal cells, particularly mesangial cells and interstitial fibroblasts. During kidney development, PDGF may mediate processes of cellular recruitment, extracellular matrix deposition, and proliferation with the constructive outcome of glomerulogenesis and vascularization. Proliferation and production of extracellular matrix components by these cells likely contribute to destructive proliferative and sclerotic responses attending proliferative and other glomerulopathies. As additional information accumulates, therapeutic targets within the PDGF system may provide opportunities to arrest destructive renal processes.