The effects of a nonstarch polysaccharide-hydrolyzing enzyme product on growth, feed conversion, ME, and digestibility of crude nutrients and amino acids were investigated in a 22-wk trial using male turkeys. Diets were mainly based on wheat, barley, and rye, and the experiment comprised 6 phases. The enzyme product contained endoxylanase and beta-glucanase activity. Fifteen replicated pens were used for studying growth and feed conversion. In 5 pens per treatment, excreta were collected on 5 consecutive days during phases 3 to 6. Ileal digesta was sampled at the end of these phases from 1 bird of each pen. Titanium dioxide was used as indigestible marker to calculate digestibility and ME concentration. In phase 6, but not in the other phases, BW gain and G:F ratio were significantly improved by the supplemented enzyme product. This was associated with a significantly higher ME concentration. With the exception of cystine, no significant effects were measured for the prececal digestibility of amino acids. Amino acid digestibility, calculated based on total excreta, was significantly higher with enzyme supplementation for 12 or 8 out of the 14 analyzed amino acids in phases 5 and 6. In phases 3, 4, and 5, the level of amino acid digestibility was higher by an average of 5 percentage units when calculated on total excreta than on ileal digesta basis. The greatest differences were found for cystine and methionine. Improved digestibilities and energy metabolizability contribute to the effects of nonstarch polysaccharide-hydrolyzing enzymes on feed conversion and growth in heavy turkeys.