Morphological and conformational transitions of lentinan (LT), a ˇ-glucan extracted from Shiitake mush-rooms (Lentinula edodes), were investigated at different concentrations of aqueous NaOH, using SmallAngle X-ray Scattering (SAXS) technique. At low NaOH(aq)concentration LT chains are self-associatedand adopt the triple helix form where as at higher NaOH concentrations the polymer chains undergo atransition to random coil chains. Also, the presence of fractal dimensions was observed through analysisof the exponential decay of the scattering intensity as a function of the scattering angle. In addition, thelateral radius of gyration was determined for LT in different concentrations of NaOH solution, indicating arigid triple helix present as a small rod-like structure. Interactions of LT with two zwitterionic surfactantswere investigated by surface tension, fluorescence, and static light scattering measurements. Experimen-tal data showed that the formation of LT–(surfactant) complexes occurred through a cooperative process.