The conformation and monolayer assembly of poly(gamma-n-dodecyl L-glutamate) (PDOLG) in a monolayer at the air-water interface and its multilayers were investigated by surface film balance, FTIR, and electron microscopy methods. PDOLG with long alkyl side chains forced a condensed type monolayer with an alpha-helical conformation. The hysteresis loop in the compression-expansion-recompression isotherms indicated that relaxation processes were operating in the monolayer. PDOLG molecules formed a polygonal network structure in the multilayer film prepared at the pressure 20 mN/m by the lifting method.