This study aimed to evaluate the effects of a probiotic and/or prebiotic additive on the nutrient digestibility of diets for growing rabbits. Twenty 50-day-old rabbits were used. A completely randomized experimental design, with five treatments and four replicates each, was used. The applied treatments (T) were the following: T1 = negative control diet (no growth promoter); T2 = diet with antibiotic, positive control (0.05% zinc bacitracin); T3 = diet with probiotic (0.15% Bacillus subtillis at a concentration of 109 UFC/g); T4 = diet with prebiotic (0.15% phosphorylated mananoligossaccharide at 30%); and T5 = diet with symbiotic (probiotic + prebiotic). The experimental period lasted 12 days, seven for adaptation to the experimental diets and to the cages, and five days of feces collection. The apparent digestibility coefficients of dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber, mineral matter, and ether extract were calculated. The addition of a probiotic and of a symbiotic to the rabbit diet resulted in digestibility similar to that of animals fed diets containing antibiotics or no additive at all. The best digestibility results were obtained with the prebiotic.