Studies have been made of the effects of sodium dodecyl sulfate (SDS) on the pasting properties of wheat, corn, potato and waxy corn starches with the Rapid Visco-Analyzer. The peak viscosity and break down of wheat, corn and waxy corn starches during heating were markedly increased with the increasing concentration of SDS. Those of potato starch were markedly decreased at the lower concentrations of SDS and then increased at the higher concentrations. The maximum setback viscosity during cooling was markedly increased for wheat, corn and potato starches and slightly increased for waxy corn starch with the increasing concentration of SDS. From the results it was assumed that the striking increase in the peak viscosity during heating might be ascribed to the complex formation of amylopectin inside the swollen granules with SDS and the increase in the viscosity during cooling might be ascribed to the complex formation of the amylose leached with SDS followed by the gelation.