This article reports the development of micropatterning technology of cultured cells by precise surface regional modification via photochemical fixation of phenyl azidoderivatized polymers on polymer surfaces. Photoreactive polymers prepared in this study included poly(N,Ndimethylacrylamide-co-3-azidostyrene), bis-4-azidobenzamide-polyethylene glycol, and poly(styrene-co-3-azidostyrene). The photochemical fixation of these photoreactive polymers consisted of three steps: 1) coating of a photoreactive polymer on a material surface, 2) ultraviolet irradiation through a photomask, and 3) removal of nonreacted polymer by a solvent. Electron spectroscopy for chemical analysis and water contact angle measurement were employed for surface characterization. Two different types of regionally modified surfaces were prepared; one was a hydrophilic polymer regionally fixed on a tissue culture dish and the other was a hydrophobic polymer regionally fixed on poly(viny1 alcohol) (PVA). Photochemical surface microfabrication permits p-order dimensional precision, which was verified by the micropatterned tissue formation of bovine aorta endothelial cells (ECs) when ECs were seeded on these surfaces. ECs adhered, spread, and confluently proliferated only on uncoated tissue culture dish surfaces or hydrophobic regions on PVA. Thus, the regionally differentiated cell adhesional regions were created by photochemically driven surface microprocessing.