Full Paper: The photochromic behaviour of optically active methacrylic polymers containing in the side chains a bulky chiral amino acid residue interposed between the backbone and the azobenzene chromophore through amido groups, such as poly[(S)-4-(2-methacryloylamino-4-methylpentanoylamino)azobenzene] [poly(MLEA)], poly[(S)-4-(2-methacryloylamino-3-methylbutanoylamino)azobenzene] [poly(MVA)] and poly[(S)-4-(N-methacryloy-2-pyrrolidinoylamino)azobenzene] [poly(MPA)] was investigated in comparison with the corresponding low molecular weight model compounds. The photoresponsive properties of the above polymers were also evaluated by circular dichroism measurements at various extent of photoisomerization and in solvents with different polarity. All the results are discussed in terms of structural requirements of the macromolecules.