Three experiments were conducted using crossbred weanling pigs (7.2 to 8.6 kg; 25 to 29 d of age) to determine the effect on performance and nutrient digestibility of .75% yeast culture (YC) additions to starter diets containing whey or one of two fiber sources. An 18% CP corn-soybean meal basal diet was used in all experiments. In Exp. 1 (n = 192), the addition of YC did not affect ADG, ADFI, or gain: feed ratios (G:F) of pigs fed diets without or with 15% dried whey in two 5-wk trials. In Exp. 2 (n = 174), ADG and ADFI were not affected by YC addition to diets containing no added fiber, 8% soybean hulls (SH), or 8% peanut hulls (PH) in two 5-wk trials. The addition of SH or PH did not affect ADG or ADFI; however, a YC x SH interaction (P < .05) and a YC x PH interaction (P < .10) for G:F indicated that the addition of SH or PH to the diet in the absence of YC reduced G:F, but in the presence of YC, G:F were maintained. In a 3-wk grower phase of one trial in Exp. 2 (n = 54), SH and PH additions decreased ADG (P < .005), whereas YC additions improved ADG (P < .01), particularly for pigs fed diets that also contained SH (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)