We investigated the molecular orientation and surface morphology of organized molecular films with regard to solid-state structures for organo-modified montmorillonites by surface pressure-area (pi - A) isotherm, inplane and out-of plane X-ray diffraction (XRD), and atomic force microscopy (AFM). From the results of out-of plane XRD, formation of highly ordered layer structure was confirmed in these clay Langmuir-Blodgett (LB) film. Further, two-dimensional lattice of long alkyl chain of organo-modified parts packed hexagonally or orthorhombically in the films. Surface morphology of Z-type monolayers on solid of organo-modified montmorillonites indicates heterogeneous modification ratio in montmorillonite surface by AFM observation. In addition, monolayer behavior on the water surface and mesoscopic morphological formation on solid of mixed films of organo-modified montmorillonite and poly-(L-lactide) (PLLA) were investigated by pi - A isotherm and AFM. Collapsed surface pressures are independent on the mixed ratio, and indicate almost constant value in their isotherms. This tendency is a peculiarity of immiscible system. From the result of AFM observation, phase separated structure was confirmed in mesoscopic scales. This phase separated morphology remarkably varied with mixed ratio. POLYM. ENG. SCI., 51: 1099-1107, 2011. (C) 2011 Society of Plastics Engineers