Abstract: Complexation of different synthetic amyloses (P(n) between 9 and 1000) with sodium dodecyl sulfate and 4-tert-butylphenol was investigated by means of microcalorimetry and circular dichroism. The results were compared with the complexation behaviour of alpha-, beta and gamma-cyclodextrins with the same guest molecules. All amyloses investigated formed complexes with sodium dodecyl sulfate in a fast reaction. In these complexes the amyloses possess a helical conformation with six glucose units per turn, which should already exist in aqueous solution before complexation. tert-Butylphenol only forms complexes with amyloses of a P(n) higher than 100. In this case apparently the amylose must adjust to complex the tert- butylphenol in a helix with seven or eight glucose units per turn. Using these methods the complexation of sodium dodecyl sulfate with amylopectin was also demonstrated