This study investigated the influence of various soluble and insoluble fiber sources and concentrations on growth performance and gizzard and cecal pH of broiler chickens challenged with necrotic enteritis (NE). A total of 2,160 YPM x Ross 708 male chicks were assigned to 8 experimental treatments (9 replicate pens per treatment with 30 birds per replicate) on the day of placement. Two control groups (unchallenged or NE-challenged) were fed a corn-soybean meal basal diet without additional fiber sources. Six additional NE-challenged treatments were based on inclusion of 3% oat hulls (OH); 1.5% oat hulls plus 1.5% sugar beet pulp (OH+SBP) or wheat middlings (OH+WM); 3% soy hulls (SH); 1.5% soy hulls plus 1.5% sugar beet pulp (SH+SBP) or wheat middlings (SH+WM). All fiber sources were included at the expense of corn. Dietary treatments were maintained across starter (0 to 17 d), grower (17 to 26 d), and finisher (26 to 35 d) phases, and digestible lysine and metabolizable energy values for the control diets in each phase were 1.26% and 3,050 kcal/kg, 1.18% and 3,100 kcal/kg, and 1.08% and 3,125 kcal/kg, respectively. The NE challenge model included oral gavage with a 10x dose of a live Eimeria vaccine containing E. maxima, E. tenella, and E. acervulina on d 14, and gavage with 108 cfu Clostridium perfringens on d 18. Bird weights and feed intake (FI) were recorded on d 17, 21, 26 and 35. On d 21 and 35, gizzard and cecal content pH was measured for one chicken per pen. Statistical analysis of growth performance and pH was conducted in contrast to the NE- positive control treatment. Chickens challenged with NE had reduced (P < 0.01) body weight gain (BWG) and FI from 0 to 21 d, 0 to 26 d and overall (0 to 35 d). From 0 to 17 d, chickens fed OH had higher (P < 0.05) FI, while feeding OH, SH, SH +WM all resulted in poorer (P < 0.05) FCR compared with control-fed birds. From 0 to 26 d, birds fed OH+SBP had greater (P < 0.05) FI, but increased FCR (P < 0.05) was only observed for the SH and SH+SBP-fed groups compared to control-fed chickens. On d 35, chickens receiving SH+SBP had reduced (P < 0.05) BWG and higher (P < 0.05) FCR than control-fed birds. Diets containing OH+SBP and OH+WM increased (P < 0.05) overall FI, but did not influence (P > 0.05) BWG or FCR. Dietary fiber inclusion and NE infection did not alter pH in gizzard or cecal contents, except for a lower (P < 0.05) cecal pH at day 35 in birds fed OH compared to control-fed birds.