The objective of this study was to biologically evaluate eight mixtures of flour and brans prepared with nonconventional foods popularly denominated 'multimixtures', which differed from each other in terms of type of bran (wheat or rice), presence or absence of cassava leaf powder and submission or non-submission to a solid-state fermentation with Saccharomyces cerevisiae for 6 h ⁄ 30°C, utilising female Wistar ⁄ UFPEL rats. Biological indices determined were food efficiency ratio (FER), protein efficiency ratio (PER), net protein efficiency ratio (NPR) and in vivo digestibility. Liver, spleen and kidney specimens were collected at the end of the experiment. In vivo digestibility of diets containing multimixtures formulated with wheat bran was superior to diets containing rice bran, presenting values from 76.5% to 82.8%, which corresponds to up to 85% of casein digestibility. The results allowed the conclusion that fermentation tended to improve food efficiency, but did not influence in vivo digestibility.Keywords Cereal bran, fermentation, food efficiency ratio, in vivo digestibility, multimixture, net protein efficiency ratio, protein efficiency ratio, rats, rice bran, wheat bran.