The discovery that both potassium and sodium salts of hyaluronic acid can exist in a double-strand helical conformation that will convert to the already known single-strand helical structures illustrates the remarkable conformational versatility of this biopolymer. X-ray diffraction was used to monitor variations in molecular conformation as a function of several independent, controllable variables, such as relative humidity, temperature, and applied tension. A scheme is presented for the interrelation of a range of hyaluronate conformations.