Hyaluronic acid (HA)was extracted in a relatively large scale from rooster comb using a method similar to that reported previously. The extraction method was modified to simplify and to reduce time and cost in order to accommodate a large-scale extraction. Five hundred grams of frozen rooster combs yielded about 500 mg of dried HA. Extracted HA was characterized using asymmetrical flow field-flow fractionation (AsFlFFF)coupled online to a multiangle light scattering detector and a refractive index detector to determine the molecular size, molecular weight (MW)distribution, and molecular conformation of HA. For characterization of HA, AsFlFFF was operated by a simplified two-step procedure, instead of the conventional three-step procedure, where the first two steps (sample loading and focusing)were combined into one to avoid the adsorption of viscous HA onto the channel membrane. The simplified two-step AsFlFFF yielded reasonably good separations of HA molecules based on their MWs. The weight average MW (M(w)) and the average root-mean-square (RMS)radius of HA extracted from rooster comb were 1.20×10(6)and 94.7 nm, respectively. When the sample solution was filtered through a 0.45 ?m disposable syringe filter, they were reduced down to 3.8×10(5)and 50.1 nm, respectively.