To understand epitaxial crystal growth of organic molecules from solution, monomolecular layers of three isoindoline derivatives formed on the graphite (0 0 0 1) surface from phenyloctane solutions were investigated by STM. The observed images showed that the layer is composed of many relatively smaller single crystalline domains than those formed by vacuum deposition. The two-dimensional lattice of the monomolecular layer of the isoindoline derivative was analyzed with respect to the graphite surface lattice. In the case of isoindoline layers at the liquid/solid interface, the epitaxial orientations were slightly fluctuated from domain to domain around commensurate orientation. It is called here "pseudo-commensurate" epitaxy. Such pseudo-commensurate epitaxy can be interpreted as resulting from the size effect; that is, broadening of Laue functions appearing in the lattice-lattice interaction equation at the interface of deposited layer and substrate surface.