Technical Abstract: Batter viscosity is an important quality trait of wheat flour. Water-extractable arabinoxylans form oxidative gels which contribute to variation in viscosity. The purpose of this study was to investigate the oxidative gelation potential of wheat flour mill streams to better understand sources of variation in batter viscosity. Thirty-one genetically pure soft, hard and club wheat varieties were milled on a Miag Multomat pilot mill. Ten flours (mill streams) per variety were analyzed for water-extractable (WE), water-unextractable (WU), and total (TO-AX) arabinoxylan content, and for oxidative gelation potential (+/- peroxide-peroxidase) (POx). WE-AX content varied greatly among flour streams (F=619) and less among varieties (F=152). Variation for endogenous oxidative gelation potential, as evidenced by Bostwick consistometer viscosity, was greater among mill streams (F=627) than among varieties (F=117). Variation for oxidative gelation with POx decreased for both flours steams (F=141) and varieties (F=97). Mill stream X variety interactions were small but significant for all traits, and were considered an inconsequential source of overall variation. WE-AX and TO-AX were significantly but not strongly correlated (r=0.66) overall. Oxidative gelation without POx had similar correlations amongst WE-AX (r=-0.65), water-unextractable (WU-AX) arabinoxylans (r=-0.71), and TO-AX (r=-0.72). Oxidative gelation with POx decreased the correlations amongst WE-AX (r=-0.49), WU-AX (r=-0.36), and TO-AX (r=-0.38). The relationship among WE-AX, WU-AX, TO-AX content and oxidative gelation potential for mill streams may indicate the molecular structure of AX, i.e. degree, pattern, and frequency of arabinose and ferulic acid substitution, is important.