Fiber ingredients in swine diets have various components that affect the intestinal tract distinctively. The objective of this study was to determine the effect of structural fiber sources on growth performance of nursery pigs. A total of 1,760 weanling pigs (initial BW = 6.12 ± 0.3 kg, 16 reps/trt, 22 pigs/pen) were used in a study with 5 dietary treatments: 1) Complex nursery diet with no additional fiber (CON); 2) CON + 2% rice hulls; 3) CON + 4% rice hulls; 4) CON + 6% wheat middlings; 5) CON + 12% wheat middlings. Fiber ingredients were added at the expense of corn and some processed soybean meal to maintain similar dietary protein levels. Using an in vitro fermentation estimation of fermentation for rice hulls and wheat middlings, diets were constructed to add similar levels of structural (non-fermentable NDF) fiber between low and high additions of rice hulls and wheat middlings. Pens across two barns were randomly allotted independent of one another and within a location block to one of the five treatments on d 0 of a two-phase study (d 0-11 and d 11-20.5 post-weaning). Data were analyzed by general linear model in R. Mortality and removal data were analyzed as a generalized linear mixed model with a binomial distribution. Contrasts tested the effect of additional fiber (CON vs treatments 2-5), effect of medium vs high fiber (treatment 2/4 vs 3/5), effect of source of fiber (treatment 2/3 vs 4/5), and the interaction of level and source of fiber. Overall (Table 1), additional fiber resulted in increased ADFI (P < 0.05) and tended to increase ADG (P < 0.10). Probability of mortality and removal was reduced (P < 0.05) when additional fiber was included.