Octadecylesters of L-1-naphthylalanine and L-1-pyrenylalanine were synthesized. Both compounds form stable condensed monolayers at the air-water interface and can be transferred onto solid plates by the vertical dipping and horizontal lifting methods to give the alternating Y-type and non-alternating X-type films respectively. The orientation and packing of the aromatic rings depend upon the deposition methods and the surface pressures, as indicated by UV, circular dichroism and fluorescence spectra. Poly-amino acids containing the pi-electron systems as a side group could be obtained in the LB films. For the Y-type films, the oligomer was obtained in the first step at 25-degrees-C, and then the poly-amino acid with a random coil was produced by increasing the temperature to 40-degrees-C, as suggested by the amide I bands at 1690 and 1650 cm-1. The conversion in the X-type film was very low compared with that in the Y-type film. It is considered that the interlayer reaction propagates by "sewing up" the amino and the ester groups facing each other at the adjacent layers in the Y-type films.