AbstractThe mesophase induced circular dichroism (CD) of biphenyl and its derivatives was investigated using the Tween 80 (monooleate of the ether of sorbitan with 4 mol of polyethyleneglycol)‐water system, which can form a twisted smectic mesophase. The sign of CD bands in this mesophase is explained by a modified C2‐symmetry rule, since it can be considered that alignment of the solute molecules in this mesophase can be elucidated in terms of a pseudo‐C2symmetry, when the concentration of the solute is comparatively high. The assignments of the electronic transitions of the solute molecules show a good accordance with results of magnetic circular dichroism