A series of 4-[4-(dimethylamino)styryl]-1-alkylpyridinium bromide (DASP-C(n)) dyes were synthesized for inclusion studies with amylose. Inclusion complexability of DASP dyes with amylose, and conformational transitions of amylose upon complexation with the dyes were investigated using UV-visible, fluorescence, and circular dichroism (CD) spectra in various dimethyl sulfoxide (DMSO)-H2O mixtures. Complete amylose inclusion occurs with DASP dyes > C-12 while it decreases sharply with the dyes less-than-or-equal-to C-12. Amylose inclusion is sensitive to the solvent composition, showing a clear transition at a DMSO fraction, PHI(DMSO) = 0.6, above which no or negligible complexation occurs. Amylose resumes the helical conformation upon complexation (at PHI(DMSO) less-than-or-equal-to 0.6) with DASP dyes but the helical state is affected by the solvent polarity, becoming loosened with decreasing DMSO content.