Syntheses and radical polymerizations of methaerylamides having (L)leucine and N-methyl-(L)-leucine methyl ester structures in the side chains N-methacryloyl-(L)-leucine methyl ester (MA-L-M) and N-methyl-N-methacryloyl-(L)-leucine methyl ester (N-Me-MA-L-M) were carried out. The monomers were prepared by the reactions of methacryloyl chloride with the corresponding amino acid methyl esters. Radical polymerizations were carried out in the presence of appropriate initiators at 60 degrees C and 120 degrees C. MA-L-M afforded the corresponding polymer with M(n)s 38,000 similar to 372,000 in high yields, while N-Me-MA-L-M afforded a trace amount of polymer at 60 degrees C and in a low yield even at 120 degrees C. Both inversion and increase of absolute value of specific rotation were observed in the transformation from MA-L-M (+1.3 degrees C) to poly(MA-L-M) (-35.7 degrees C). Changes in the CD spectral pattern and the conformation of the leucine moiety were confirmed from the monomer to polymer.