The structure of films of stearic acid spread on MgCl2, solutions in collapse state was investigated by using atomic force microscopy (AFM). These collapse states have been suggested to arise from the buckling of the monolayer, concomitant followed by a cooperative folding over to form a very stable trilayer film structure (i.e. monolayer plus bilayer). The Langmuir-Blodgett films of this state reveal clearly a trilayer assembly formation from AFM with almost no defects.