Urolithiasis is related to injuries of renal epithelial membrane. However, the microstructure of injured renal epithelial cellular membranes and the mechanism for the adherence of stone microcrystals have not been yet clearly understood. The defect formation of Langmuir-Blodgett (LB) film of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) injured by potassium oxalate was investigated with the aid of atomic force microscopy (AFM) and fluorescent microscopy. The effect of the defects on the growth of calcium oxalate monohydrate (COM) was investigated by scanning electronic microscopy (SEM). The circular defects in the LB film could induce circular aggregation of COM. The diameter of the circular patterns ranged from 3 to 150 μm. In the patterns, the COM crystals existed as needle-like, quadrangle and anomalistic shape with a size of about 1～3 μm. However, no circular patterns of COM crystals were formed if the LB films had not been treated with oxalate. In this case the COM crystals with a size of about 5～10 μm randomly grew at the LE/LC boundaries of the LB films. The effect of various LB films on the nuclea-tion and growth of COM crystals follows the order: the LB film with defects treated by potassium ox-alate>>LC/LE boundaries in normal LB film＞normal LB film except the LC/LE boundaries>>bulk solu-tion. The above results were discussed from the points of active sites in the defective LB films and their ef-fect on COM nucleation.

Key words: Langmuir-Blodgett film, defect, calcium oxalate, DPPC, crystallization